JMK Engineering Inc.

Adding custom PV Panel to PVsyst

2025-01-07T00:00:00-04:00

PVsyst has one of the best databases for PV Solar components available, but even they won't have everything. This tutorial will go through the steps needed to add a custom PV panel to your database.

Importing PAN files

The easiest way to do this is if the manufacturer has published their PAN files. I'm using the 144HC M10 SL Bifacial Module and am lucky. Heliene has published their PAN files, you can find them on the product page.

Step 1 - Download

Download the PAN files. If there are multiple modules in this series, the example I'm using has 5 different power ratings (520-540W) the download will typically be a .zip file.

Step 2 - Open Import Components Dialog Box

Next, open the Import Components Dialog box in PVSyst. In this example select the Import Components from a ZIP file.

Step 3 - Select the PV Modules to Import

If you are only importing a sub-set of the modules in the ZIP file, you can select the one that you want. I typically will import all the modules, it really doesn't take up a lot of space.

If the modules don't show up immediately, you may need to click the browse button and open the folder from the Windows Temp folder directly. The button should take you to the root folder, where it placed the un-zipped file, directly.

Finally click the 'Import >' button.

Step 4 - Check that it worked

When its done, you should be able to open any project and check to make sure that the components were added. They will be highlighted in the dropdown box.

And your done

That should be everything. If you need to import a complete custom panel, without the PAN file available, there is a way to do that too. I will add that tutorial on another Tuesday and link it here when its ready.

Quick Economic Analysis of the Solar/BESS

2024-12-10T00:00:00-04:00

To this point we have determined if the PV/BESS system could technically work to replace a standby genset, and also provide some relief from utility expenses.

The first step we took to determine if this is going to make sense is a very simple payback in today's dollars, and in both cases the payback in years was very very long.

I don't want to stop there though, so I want to try two more things:

Calculate IRR (Internal Rate of Return)
Compare a standby TCO (Total cost of Ownership) and the PV/BESS system

Setting up

First we need to continue to set up the project for this analysis.

Project Life: 25y
Inflation: 2%
Energy Cost Inflation: 1.65% per year [1]
PV O&M Costs: $2/kWdc installed
BESS O&M Costs: 1% capital per year
PV Degradation Rate: 1% per year

The BESS and PCS are sized for the standby power, and with this sizing it should be able to continue to meet the demand over optimal over the entire project life.

We have one more assumption that will make this a little easier:

The load profile stays approximately the same over the project life [2]

Cash Flows and IRR Alone

Using the assumptions and variables above, I'm able to calculate the sample load flow, and project balance for the 8000kWdc configuration.

Configuration 1 Cash Flow

With this cash flow diagram we can calculate the IRR of the project to be ~3.02% IRR.

Configuration 2 Cash Flow

The smaller system doesn't fair much better at ~3.01% IRR.

Not the whole story

Luckily for us, or at this this project example, this isn't the whole story. The purpose of this system is not just to decrease utility expenses, in fact, that is a side benefit of the system, and as such the project shouldn't be evaluated on that alone. In fact, it is this standby power requirement, and the full 24h of BESS that is driving the capital cost of the project. In fact the peak optimal demand [3] is only 2.3MW, so the minimum BESS size needed to meet this requirement is likelt in the 5-8MWh range [4] not the 15MWh needed to accomodate 80% depth SOC for the standby load.

So, what is another way to look at this? Well I already mentioned it, it is the TCO of the alternative generator.

For this analysis I'm using a 1MW diesel genset, this is going to be slightly higher than that of a natural gas genset because of the need for more frequent full load testing, fuel costs and fuel cleaning/maintenance costs.

Total Cost of Ownership

I was hoping to hop online and then quickly find a couple of tables outlining the TCO for various standby gensets based on size, location, fuel type, etc. To my surprise I couldn't find a thing, and the one partly helpful PDF that I did find had a MAJOR typo [5] and the TCO tool it links to is broken. It did however give me a starting point for the analysis and assumptions.

Tank Size: 3600L
Load Bank Testing: Full load, 8h, every 3 years
Diesel Fuel Maintenance: Full tank, every 2y, $1/gal
Run Hours: 20h no-load, 40h with load per year
Annual Maintenance: $500 for the tech to do the work and $1/kW for materials.
Capital Cost: $500/kW [6]

Fuel Price

This is a tough one, so what I used was the USA average on November 25, 2024 for on-road, it may be $0.25 /gal cheaper for off-road fuel, but the diversity across the USA and seasonally, more than covers this difference.

The Genset Used

I'm writing this on November 29th, and it is suprisingly hard to find people to give some numbers and detailed specs for this exercise. Luckily I was able to find a generator spec sheet for a Cat C27 that had the fuel consumption rates that I needed.

With these rates I interpolated the "average" load rate that I used for the on-load serving time, and I used 1/2 of the 25% load for any unloaded standby running time. That is probably low, but I think that it will work for this example.

TCO Results

For this example I end up with a TCO of $610k for the standby generator option.

To tell you the truth, this was a lot less that I was expecting, and I think, that there are some maintenance costs that I don't have in here correctly yet, but it does line up closely with one of the only examples of TCO that I found.

Comparing with PV BESS Options

While that graph looks damning, it start way down and only keeps going down, when you compare it to the project balances for the two solar options above, it is basically a straight line.

Financial Conclusion

I'm an engineer, not an MBA, but based on just these metrics, I think its inconclusive. The IRR of the PV/BESS option will not justify the project on its own, the average cost of capital in 2024 was 7%, the 3% we calculated doesn't come close.

The TCO for a comparable standby diesel generator doesn't help move the needle toward PV/BESS, at least for this example.

Over the holidays I will try a similar analysis with different electricity costs, local irridiation, and diesel fuel prices to see if the challenge here is the relatively cheap power and diesel fuel, or if the cost of batteries are still too high to allow for a project like this to stand on its own.

I'm not done yet.

Footnotes

[1]	I'm assuming that this is constant. We used the number published here

[2]	For an established industrial/manufacturing site this is going to be accurate, and when there are changes to the process that will affect the load of the system, these changes will have their own economic analysis that would take into account the new load profile established by the PV/BESS system.

[3]

Optimal peak was defined in the first post of this series. It is the hourly peak over the average for that day. The BESS would ensure that the daily load would stay at or below the calculated optimum. The PV generation does a decent job following the load profile, but the typical peak is slightly later in the afternoon, when the PV drops because of both heat and sun angle.

[4]	Because the minimum BESS required for the standby was so much larger than that needed for the demand shifting I didn't calculate the actual energy needed for this purpose. That may be an anlysis for another post.

[5]	The PDF is comparing the TCO of diesel to natural gas, trying to sell the natural gas option as having a lower TCO, however they suggest that the TCO is the same $110,000 for a 150kW unit and a 2MW unit. I'm pretty sure its a copy/paste error, but in any case its not useful for this.

[6]	This is assuming about $100/kW for installation and $400/kW for the genset, complete with a full tank of fuel.

[7]	The COst of capital value is from this page compiled by Aswath Damodaran

5 Reasons your Power System Study Needs to be Updated

2024-12-03T00:00:00-04:00

A power system is not a static system, there are always changes, some big and some small. The big changes are obvious at the time, but the small changes may add up to something that affects the operation of the system in an unintended manner. The protection system is particularly susceptible to this.

Today we are listing out 5 times or situations when it is time to update your power system study, or at least an audit to make sure that it is still valid.

add or removing equipment
changing a start from across the line to VFD or softstart
changing the protection settings, even a little
changing a fuse manufacturer (even if its the same rating)
its been 5 years

Changing Equipment

If the site has added new equipment, or simply changed a couple transformers to a high-efficiency model, there is a liklihood that there have been changes to the short circuit current and protection settings in that area of the system.

This will affect at least two studies, the short circuit duty and incident energy.

The higher efficiency transformers have a higher short circuit current, in extreme cases this may push the downstream equipment outside its short circuit duty.

Changing to VFD

In a lot of cases it makes sense to switch to a VFD for variable loads. This will give the process more control and likely reduce the system energy demands.

Changing to a VFD will also affect the back feed current into the system during a fault, UNLESS the fault happens during full load AND the VFD has an online bypass contactor. This change will affect the incident energy at that bus during the fault, typically lowering the IE and Arc Flash Boundary.

The VFD will also introduce harmonics on the system, this is especially true if there wasn't any filtering installed at the time. If the VFD is a significant portion of the load on the bus, and there have been mis-operation of protection or electronic equipment at that location, a harmonic analysis may be required.

Changing Protection settings

I've been there, its late and a piece of equipment is tripping so you increase the pickup until it stops. Or maybe the process load has changed but the nameplate has a similar spec so the process team didn't bother to let you know.

By changing these protection settings, there may be affects upstream that aren't intended, and maybe these affects won't be seen for years until the plant load increases, or there is an abnormally high load day.

If protection settings have been changed, even a little, I recommend re-visitng the protection coordination study, and in some cases it will require new arc flash labels for the affected equipment.

Changing fuses

This is the same as the previous point. Changing fuse manufacturers WILL change the curve of the equipment. If its a fuse for a specific piece of equipment, then it is likely fine. I would double check the manufacturer requirements to make sure, but that would be all I would do.

If it is feeding a distribution panel, transformer or medium voltage switchgear, then my recommendation is the same as above. Have the protection coordination study reviewed to ensure that there are no adverse affect.

Time

After about 5 years there are likely enough small changes within the system, and likely changes on the utility system that its time to review the main four power system studies.

In most cases the short circuit will be the same, unless the plant transformer or primary distribution system has changed, but there will be changes on from the utility system that will affect the Incident Energy, likely minor changes throughout the plant that affects the load flow and protection coordination.

Closing

If any of these five reasons rings true at your facility, let me know. I'm happy to discuss to see if I think that you need to start from scratch (unlikely), a review of the existing system vs the old reports, or a couple tweaks to the existing model and report.

I look forward to working with you.

PV Solar Development Process EPCO

2024-11-26T00:00:00-04:00

I started to write the entire PV Solar Development process in a single article and it started to get too long for the internet. In the first paragraph I even mention that each phase could be a book and this would be a summary, but I still wasn't able to summarize it enough.

If you attended the presentation I did with Net Zero Atlantic in September, this is a section that I only dedicated a single slide, and this is the part where I expand on it.

If you haven't seen the first part describing the development process, you can find it here that jumps right into the first stage of a PV Solar Development project. For everyone else, lets get into the engineer, procure, construct, operate (EPCO) stage of the PV Solar Development process.

EPCO Stage

The EPCO stage is the execution stage, it will include the following phases:

Detailed Design and Permitting
Procurement and Construction
Testing and Acceptance
Operations

Detailed Design

Detailed design starts when the project scope and business model is sufficiently complete that the:

interface to the utility,
high level one-line,
real estate, and
over all project requirements are written down and likely aren't going to change in a material manner.

This is an important decision gate and if one of these items change, then the ripple affect will result in a lot of re-work.

The detailed design process will follow a framework similar to the one I outlined a few weeks ago, but the specifics will be different for every project execution type, and where you are as part of the project team.

For any project that has a mix of commodity and custom equipment, I suggest developing the design first to develop the requirements for major pieces of equipment, then the interface for this equipment.

For example, if the project is using large central inverters vs smaller string inverters, develop the specifications and requirements for these so that they can be sent for final selection and procurement before starting the detailed LV string design.

Some other major pieces of equipment that should be prioritized include:

Medium Voltage switchgear
Generator Step-up (GSU) transformer [1]
Utility SCADA and P&C cabinet [2]

The final part of the detailed design stage is procurement.

Buying Early

My suggestion today, is similar to that almost two years ago, research possible lead time critical paths early and make decision required to keep the project on track.

This is especially true for high-voltage equipment and power transformers. The lead times that I have been quoted at the time this is published is up to 54weeks for a 10MVA power transformer and longer for 69kV gang-operated switches.

The supply chain is a mess, and with the recent election in the USA, I expect that it will be even more chaotic over the next few years.

Permitting

Like all projects there are a varity of permits that will need to be obtained before starting the construction phase. To ensure that the project continues to be feasible these some of these permits should be in hand during the FEED stage of the project.

In a lot of cases there will be permits that will be required to obtain other permits. To ensure that the permitting process doesn't affect the project timeline, I suggest that you develop a detailed permitting plan early in the project developing process.

Include all the inter-dependencies that these permits have and assign project team members as "owners" for the various permits and agreements.

Some of the permits that will be required for all projects include: [3]

Land Use Permit
Environmental Permit
Grading Permit
Engineering Design Permits (structural, civil, building, MEP, etc)
Drainage Design Permit
etc

Procurement and Construction

Depending on the project structure, and if there have been any pre-purchased equipment, like some of the long lead items mentioned above, the procurement & construction process will be different in the details.

In general the procurement and construction process will start with the selection of the EPC and then the execution of the project execution plan (PEP).

Part of the scope for the EPC is the development of the Testing, Commissioning, and Acceptance program. This program is approved during the construction process, but development should be started during the detailed design.

It is this program that is executed int he next project phase.

Testing and Acceptance

There are generally various levels of testing and acceptance during the project construction and commissioning process.

There are 5 levels of testing and acceptance during the commissioning process.

Level 1

Level 1 includes the acceptance of equipment at the factory, before being delivered to site.

This includes factory acceptance tests (FAT) during the procurement of major equipment. The FAT should be witnessed by the owners representative and have a written report to be accepted. This ensures that the equipment is as designed when its leaving the factory.

For commodity material and equipment a shop drawing review and acceptance is all that's required.

Level 2

Level 2 includes the quality monitoring during construction. This includes inspecting laydown and storage areas to ensure that the equipment is protected, auditing material acceptance reports to ensure that the material that has been paid for is on site in a as-new condition, etc.

Level 3

As the equipment is installed it will be tested to ensure that it hasn't been damaged and operates as per the detailed design.

Some of these tests include:

Calibration tests for measuring equipment
MV/HV cable tests
LV Cable meggar and continuity testing
etc

Level 4

Level 4 is the start of functional testing. This can start when specific areas have substantial completion of the construction process.

These tests are called start-up and Site Acceptance Tests. All parts of the system should be tested with load to ensure that they operate during normal and abnormal [4] conditions.

These tests will include the following systems, at a minimum:

inverters,
protection & control (P&C),
site SCADA and Energy Management System (EMS),
UPS,
building services, if required (security, HVAC, etc),
Grid interface

Level 5

Level 5 acceptance is operating the plant during various time periods without interruption. For example the time periods for acceptance could include:

In my experience that first one, the 24h test, is the hardest to reach, after that the majority of the bugs have been worked out of the system and it will be mostly smooth sailing.

The next hardest is the 30d. During the first 30d most of the normal-abnormal system operations will have happened.

After the last time period acceptance the system is ready to be handed over to operations.

Operations and Maintenance

It is common that the EPC will have a contract to operate the facility for 1-3years, and then transitioning to the owner after that period, or a contract term being extended for 3-5 years on a renewable basis.

During this phase of the project the site is operated based on a O&M plan for the project. This plan will include (at a minimum) the following:

Organization chart,
Preventative Maintenance Schedule,
Maintenance Task frequency,
Spare parts management,
PV cleaning method and schedule,
Training program and schedule,
Performance monitoring and optimization,

Closing

These first 4 parts outline the process of executing a utility scale PV solar project.

Continuing this series I will be getting into the details of different parts of the solar project from: - off-grid vs on-grid, - defining the project (maximizing energy, grid services, exportable energy, etc) - discussion on central vs string inverters for utility scale projects - etc.

I don't have a schedule for developing these, but if there is something specific that you would like me to cover, contact me.

If you like what you have been reading and want more, I have a newsletter than I write on these topics and others.

Footnotes

[1]	This is the power transformer that will transform the voltage to that of the point of common coupling/point of interconnection.

[2]

This is a negotiation that for some utilities and regulators may take a longer time than would seem necessary. This is especially true for utilities that are integrated and traditionally include generation, transmission and distribution. They don't work with independent power producers (IPP) and may request requirements that will drive the detailed design process.

[3]	This list is VERY far from all inclusive. I strongly recommend working with a local team to determine all the permits and agreements needed for the project.

[4]

I'm not sure why, but the abnormal part seems to be missed on a lot of smaller projects. When I'm reviewing FAT and SAT test plans I always look at them with the eye of how can we induce abnormal conditions to ensure that the equipment will operate in a predictable manner. It is critical that the system can transition from an unknown/abnormal state to a known/normal state without damage (or limited damage) to the system.

[*]	Featured image by Jonathan Cutrer

BTM Solar/BESS Case Study - Finding the right size

2024-11-19T00:00:00-04:00

In the previous post I introduced the example case study and ran through the initial calculations with a 8000kWdc PV system.

At the end of those calculations we recognized 2 things:

BESS is expensive and driving the cost of the system
The load profile is very summer heavy.

In this run through the calculations we will see if a smaller PV system will have a similar cost savings with a lower capital cost.

The main role of this system is to power the critical systems, that have an average load of 500kW, and to have a minimum storage of 24h for the cases when there isn't enough PV to fully charge the BESS during extended outages.

Smaller PV Solar System

For this pass through the calculations I'm using 4200kWdc/3300kWac of solar with a 15deg tilt.

The previous 30deg tilt is great if we are looking of the most MWh over an entire year, but since the load is such summer heavy, a 15deg tilt makes more sense. It will not have as much production during the winter months, and will have slightly more for the summer months.

This generation profile looks like:

Expected PV Solar Generation

This has a similar profile/look to the generation profile last time, but much lower peak and slightly more drop off in the winter months.

During the winter months the peak solar matches closely to the peak load from the plant, be it a bit early.

4200kWdc generation vs plant demand - January

In the summer the peak plant demand is much higher than the solar generation.

4200kWdc generation vs plant demand - July

Since there is much less solar, there the instances where the net demand is negative are much fewer, and smaller than in the previous example.

The maximum potential export is approximately 2MW vs the 5MW in the previous example.

In fact, based on our calculations there shouldn't be any scenario where the net generation will result in energy being shifted over days. All generation will be able to be absorbed on within a 24h period.

Daily net demand - energy

Sizing the BESS

In this scenario the driving factor for the PCS is the maximum net-demand, however in this case it is much load, including a safety factor the PCS should be specified as around 2.6MW.

The BESS storage size is going to be the same as the critical power specification, or 24h* 500kW = 12MWh. This is a 2MWh reduction from the previous example, and the minimum based on the Basis-of-Design (BOD) specifications.

Configuration Cost Savings

This configuration has the potential to produce 8,090 MWh of generation and save a total of 16MW of total excess demand charges. This results in a total annual cost savings of $684,997/yr.

Configuration Capital Cost and Conclusion

The expected capital cost for this system is approximately $12,960,000, with the BESS accounting for $7,500,000 of this. With some tweaking of the design, including lowering the time period needed for the critical power storage from 24h to 12h the payback for a project like this could be improved.

The placement of these projects make a lot of sense in areas that have:

high utility costs, both energy and demand
low power reliability
long lead times for utility connection

I want to elaborate on that last point. If a facility is interested in expanding faster than the utility can accept that load, whether they are transmission, generation or simply personnel constrained, a PV Solar/BESS system may be the best way to get that new portion of the plant online without increasing your demand and energy requirements for the facility.

If you have any questions, or would like for me to do some of the front end work for your project, contact me below.

What's next

I want to continue developing this project with the assumption that the project will operate with this configuration. How will integrating into the existing power system look? What areas of the plant will need to be modified? How will the scop of work (SOW) be laid out to ensure that the project can be a success?

A Case for Solar and BESS for Utility Savings

2024-11-13T00:00:00-04:00

I have been thinking about behind-the-meter (BTM) solar generation for years, basically since I was at a cement plant in Kansas. The image above was taken when I was on-site, there are acres and acres of limestone mine that isn't being used, and wasn't scheduled for reclamation for decades.

Two years ago I drafted a behind-the-meter solar landing page for developing these type of projects. However, since then I haven't promoted the service, or developed any background information on what this would look like.

This is the first post to rectify some of that.

BTM Project Setup

This project is based on a load profile for a modern manufacturing facility in a warm climate. Like most large manufacturing there is ample roof space for solar and we have assumed there is plenty of physical space for any modifications needed, including BESS.

Existing Power System configuration

The existing power system has two 10MVA trains for powering two 12.47kV primary voltage circuits that feed three main areas. They are configured both in loops and primary selective depending on the phase that they were built.

I put together a composite demand for the facility for 2022 and using that information prepared the following load profile.

Annual Power Load

From this load profile I can see two specific trends. One that the load follows the temperature, starting in April and ending around October. The other is there is a obvious weekly trend.

Basis of Design

The basis of this design is the premise that with on site generation and storage can reliably reduce the utility expenses of the operation and provide energy for critical power systems.

For this design I've assumed that the critical power load is a constant 500kW, and that we will require at least 24h of storage for the situations where there is extended utility outages, coupled with low PV solar.

The first step is to figure out the correct size range for the solar system such that is meets the primary and secondary goals.

Limitations

The plant can't export into the utility. There are two reasons for this limitation:

This arrangement makes the integration more complicated,
The low load period is likely low for the entire system meaning that the rates that will be available to the plant will not be great.

Sample Project

For a project that includes PV Solar, we first need a site. For the first pass of these example projects I'm going to use Arizona. Its weather matches the natural seasonal load profile of the plant load which means that I don't have to do any shifting of the load data to make it work.

For our first pass I'm setting up the solar system to have 8MWdc of panels with a 30deg tilt, and to help flatten the production, and account for the temperature de-rating of the panels, 6.3MW of inverter capability. This is a drastic inverter under-size for most applications, but for this I think it makes more sense to ensure that the critical has capacity needed.

Expected PV Solar Generation

With the undersized inverter the generation profile is extremely flat over the year, with only a dip during the winter months.

PV Solar Generation vs Plant Demand

There are two interesting areas, the winter lows and the summer highs. Looking at them a little closer we can get an idea about how much PV Solar generation will compare to the plant load, and from that how much storage will be needed to shift that generation.

PV Solar Generation vs Plant Demand - Winter

PV Solar Generation vs Plant Demand - Summer

Sizing the PCS

There are three roles for the storage system:

The export power peak
The excess demand peak
The critical power load

This means that the PCS, the portion of the BESS that charges and dis-charges the batteries needs to be sized to the maximum export peak first. From the graphs above we can see that is in the winter months. To assist in saving on the utility bills, the storage should also be able to generate limiting the monthly peak to the optimal.

Note

I've calculated the optimal peak on a daily basis.

This has been defined as the demand load in kW where the total daily energy is the same as that of the recorded load.

Export Power Peak

This is relatively easy to calculate, its the minimum net plant load (PV Solar Generation - Plant Load). In this case the minimum net plant load is -5000kW.

The PCS will have to be able to absorb this generation.

Excess Demand

The maximum excess demand, on any month, is 2.2MW.

Critical Power Load

Both the export power peak and excess demand are an order of magnitude higher than the critical power load.

PV Solar Generation vs Plant Demand - Energy

Sizing the BESS

The C-Rate is going to be the limiting factor for the speed at which BESS will be able to absorb or discharge. A lot of storage systems today are rated for 1C, however, for this example I want to assume a C-Rate of 0.5C. This example is very early in the total design process and we don't want to design something with really sharp pencils.

So, assuming a C-Rate of 0.5 the minimum kWh will be 2x the PCS size of 5MW, or 10MWh.

The size needed for the critical power system is 500kW for a 24h period, making this portion of 12MWh.

Next we need to confirm that the there is enough storage to shift any excess generation to the next day. This is 14MWh on the highest excess day.

PV/BESS and Potential Revenue

We now have the solar size, PCS and BESS specification.

Solar - 8000kWdc
PCS - 2.2MW
BESS - 14MWh

With this information we can calculate the utility savings. Since this example project is in Arizona I have used Arizona Public Service (APS) tariffs. This gives me the following costs to work with:

Demand Charge = $20 /kW
Energy Charger = $0.04421 /kwH

Excess Demand Savings

The excess demand charges have been calculated by picking the day each month with the maximum demand versus the optimal demand for that day. This will be the maximum demand charge that can be saved.

For this example, this results in a total savings of $327,303 per year.

Energy Savings

Since this project assumes that all of the generated energy will be absorbed by the system, this means that the total generation will offset the energy bought from the utility.

The total generation is expected to be 15GWh resulting in a saving of $669,410

The total revenue savings is expected to be approximately $990,000 per year.

Capital Cost

The expected capital cost for this system is likely to be in the range of $18m - $20m [*]. This total is only for the system to the plant primary voltage power system, no power system configuration or integration costs.

Smaller System may be better

It doesn't leave a great payback, so I think I have over-sized the solar system. I think a smaller PV Solar system will provide all the benefits, with a smaller capital expense, the cost of the BESS is driving the capital cost.

I will write up this smaller system next.

Footnotes

[*]

We have calculated the capital cost using a total solar cost of 1300 USD/kW this is based on the numbers from fastercapital.com and verified by a couple of PV developer friends. The BESS cost is likely high at 500 USD/kWh according to a couple suppliers, but by using this capital cost this high will likely cover the power system integration, and other costs associated with a project like this. This cost was referenced from exencell.com.

My Preferred Design Process

2024-11-05T00:00:00-04:00

The first question that I ask when I'm approached to help on a project is, "What's the scope of work?". But, about 50% of the time the person asking doesn't really know. But, unless it is really early in development they DO have a budget. Which I always find weird, how did they develop a budget without knowing what needs to happen. So there is a dance and we come to some sort of agreement and move forward.

When I first noticed this happening when I started JMK Engineering, I developed an internal document that I would share with clients and more often their project managers that were thrown into the deep end without training. It was a one page design project framework that they could use to put together their gantt charts, etc.

I think its time that I share it with anyone that's interested so that we can continue to develop it. Work on the same page.

This document starts after the business development and front end engineering and development (FEED) has be completed. I may have to create another one for that part of the process, I've already talked about the FEED for solar projects and its something that can be made more generalized.

This also assumes a design-bid-build process, but can be massaged for a design-build or any other project execution method.

Design Project Framework

This project framework is from the context of the engineering firm versus the client.

This framework has three columns:

Project Phases
Drawing Tiers
Document Tiers

Project Phases

These project design phases are slightly different from the Project Phases that I mentioned in the cookie post last week. These phases are just there as a way to break up Phase 1 and 2 (and a little 0) in that example.

Within the project phases we include some pre-award phases, these would include the FEED, RFP development, the business Basis of Design, etc.

At the end of each phase there is a decision gate. Once that gate has been passed making a change becomes more onerous. As like any process the next step depends on the previous and that means as the project develops more and more parts of the project start to tree out and depend on the core documents.

Drawing Tiers

There are a lot of different drawing types and styles. They include:

P&ID
SLDs (One Lines, Single Line Diagrams)
General Arrangements
Network Diagrams
Process Flow Diagrams
Control Schematics
I/O Schematics
Equipment details
Elevations
Panel Layouts
Wiring Diagrams
etc ...

The tiers for these drawings indicate the when they are developed during the design process. For example, one of the first drawings that I will sketch is the SLD for the project, or redline the existing SLD with the new project information.

From there the layout of the equipment is decided, at least the general areas. The west end of the plant, this general address, etc.

The drawings will continue to be development and refinement throughout the project design process.

Document Tiers

Similar to the drawing tiers above there are documents that are produced during the design process.

Some of the typical documents for most industrial projects are:

Functional Narrative
Naming Standards/Scheme
Basis of Design
Design Memo
Load List
I/O List
Functional Descriptions
Process Narratives
Control Narratives
Instrument List
Material List
Cable List
etc ...

The larger and more complex the project, the more of these documents are used.

When are the documents issued?

For each of the project design phases there is agreement or approval from the project stakeholders. What's assembled for the phase will be drawings, reports, memos, etc of differing levels of completness.

The revision description will typically read:

Issued for Review (IFR), or
Issued for Approval (IFA)

A review package will typically be from 10-50% complete. A approval package will be anywhere from 66-95% complete, in any case the substaintial topics will be figured out and included in the document.

The Tier Flow

The drawing and document tiers are broken into 4 levels, starting at 0, the initial sketch level. Tier 0 is where the initial business development and front-end engineering is fleshed out.

By the time that the fourth tier of drawings and documents are completed and ready for implementation.

How does this help?

The hardest thing about any design project isn't the technology, or complexity, or integrating into an existing system.

Its communication.

Communicating the project requirements, from business, technical, operational, etc is rarely the easiest part. A lot of engineers don't talk business, and vice-versa.

Having a process and clear breaks to make sure that the project design is meeting the goals, and staying within the initial scope, is a great way to stay on course. Its a good place to make sure that communication is clear and for everyone to ask questions, clarify anything that has been put to paper, etc.

Decision Gates and Cookies

2024-10-29T00:00:00-03:00

Something that I seem to continue to have to explain to clients is the importance of having a good decision process so that when a decision is made its understood that changing it will have a lot of ripple affect and will effect budget and schedule.

That doesn't mean that changes can't happen, just that there needs to be a process that has points of no return. In the industry they are sometimes called decision gates.

Once the project goes through this gate they can't go back without impact to the budget, scope and/or schedule.

For overall project phases from the owner/client perspective every project has 5 phases, starting at Phase 0.

Phase 0 - Deciding the standard. This is the phase that the business development and FEED flows into.
Phase 1 - Schematic Design. This phase the design is sketched out, meeting the requirements of Phase 0.
Phase 2 - Detailed Design. This phase takes the decisions that were made in Phase 1 and continues the development through to Issued for Construction
Phase 3 - Construction. This phase executes on the design.
Phase 4 - Testing and Commissioning. This phase makes sure that the final construction meets all the requirements developed and communicated in Phase 0.

Cookies to the rescue

If this isn't something you have experienced an analogy may be baking cookies.

In the initial project development phase, where the company or developer sees a need to improve their business this is called the business development and front end engineering design stage.

For this analogy the results of this process are that you need cookies, you want them home baked and they are going to have chocolate chips.

Lets start the process.

Phase 0 - Deciding the Standard

In Phase 0 we start looking through cookbooks and someone in the house would like them to be a bit healthier, Dad is on a health kick and wants to make sure they are full of nutrients. Also grandparents are coming over this weekend so we should make sure that there are lots of them.

The major design requirements are decided:

chocolate chip cookies with,
nuts and,
at least 3 dozen.

Phase 1 - Schematic Design

Next we need to decide on now the baking process is going to work.

Do we have space to make the ingredients? (general arrangement) Do we have nuts in the house? (major/special equipment) Do we have the recipe? How fancy are these cookies? (process flow)

We decide that the cookies are going to be simple, not back of the chocolate chip bag simple, but not 15 step with a 48h chill of the dough and browned butter either.

We also have nuts in the cupboard so we don't have to make any special trips to the store to get these cookies made.

Phase 2 - Detailed Design

We dig out a couple cooking books that are gathering dust above the fridge and find a few great options that meet all the requirements from Phases 0 and 1.

We make sure everyone in the house (the stakeholders) agree on the recipe and we are ready to start baking (construction).

Phase 3 - Baking/Construction

The recipe starts with creaming the butter and sugars, then in a separate bowl add the dry ingredients (except the chips and nuts).

Next we mix the dry ingredients into the creamed butter.

Finally we start stirring in the chips and nuts.

At this moment Dad gets off a phone call and decides that he would like to give some of these cookies to his friend, but he's allergic to nuts, so the cookies can't have nuts in them.

You can't go back

So at this point we have already passed through 3 decision gates and during this entire process nuts were a decided scope for the project.

They can't be removed now, the design relied on the nuts, and since construction, I mean baking, already started we will have to go back to Phase 2 to re-design the recipe (for cookies its just removing the nuts afterall) and start the baking process again.

This late decision affects:

the timeline, the baking takes longer;
the budget, we need more ingredients
maybe quality, the recipe we chose may be best with nuts so we need to either find a different one or have inferior cookies.

Back to Electrical design

The types of decisions that are made during the design process have implications down stream from the project. Sometimes this is easy like deciding on an equipment vendor that has specific advantages over others and building a design around it, or maybe its something less obvious like changing the control voltage from 24Vdc to 125Vdc because that's what the breaker vendor recommends, but all the relay contacts need to be changed out for that breaking voltage.

In this specific cookie case, removing the nuts is like removing a custom feature of the design. A feature that was prominent very early in the project, and then was relied on throughout the entire design. Removing it may appear to make the entire project "simplier" but it will also require starting some parts of the design from scratch, all the way from Phase 0 through to where we left off at Phase 3.

What about Phase 4?

In this cookie example we didn't get to Phase 4, but this is where the baker gets to taste their cookies and confirm that they are as tasty as they expected.

I hope this helps explain why its important to have that process. I prefer to be involved with a project at the very beginning, when the client just had that shower thought and wonders if its a good idea or not. That is rarely the case, but it really helps prune ideas to a few options that can be further developed in development phases so the options are clear moving into Phase 0.

MVP Electrical Safety Program

2024-10-08T00:00:00-03:00

This week in my newsletter I wrote about the Plan-Do-Check-Act cycle with respect to electrical safety programs, or really any project that seems really big when you have a blank piece of paper.

In this post I want to talk a little about what I think should be included in the first published electrical safety program for a company/site. The MVP, the minimum viable program, taken from the idea in start-ups of the minimum viable product. I wrote about this a little before, but I think its time to expand on that.

What is an Electrical Safety Program?

Let's start with a quick definition so that we are on the same page.

Electrical Safety Program a documented system consisting of safety principles, policies, procedures, and processes that directs the activities appropriate for the risk associated with electrical hazards. [1]

Breaking this down a little the important terms for the MVP are:

documented - it has to be written
policies - this is based on what the company does and the type of work that they do. The policies will be different for an electrical contractor, plant electrician and office worker.
procedures and processes - I think of these are the same thing. The procedures are the written down checklists for implementing the processes.
risk associated with electrical hazards - notice that this definition doesn't mention arc flash, labels, or PPE. Labels aren't a MVP.

Documenting

If it was me I would start a sphinx project to start typing text documents and make sure that I'm tracking changes using git, but I'm very nerdy and I'm always going on about lock-in and text documents are the best way to prevent lock-in. Since you aren't like me, a simple Word or LibreOffice document is perfect.

Policies

If your company does electrical work on your site, or customer's, then you need to determine how you want to handle energized work, whether you do it, or not, and how you will document that work.

There are other hazards to consider but for the most part the two you should start with are:

Arc Flash
Shock

Procedures and processes

For the MVP you probably don't need to include much here, but you should start including:

Job briefing checklist (Job safety plan, etc)
Energized Electrical Work Permit
Lockout-Tagout Procedure

Risk Analysis

There are two parts of a risk analysis, the severity of the risk and its likelihood of occurrence. Until you have an Arc Flash Analysis you will have to use other methods to determine the likely energy levels when exposed to energized parts.

The MVP Electrical Safety Program Itself

Everything before this is essentially what an electrical safety program is, but it doesn't include what the document should include.

The best thing to do is to list out the questions that need to be answered, the post that I linked to above has a lot of good questions to start with.

I would start a table of contents that includes the following:

Introduction
Roles and Responsibilities
Job Safety Planning
Safe Work Practices and Procedures

These are pretty wide open as they are, but its a start. The development of the electrical safety program should have a clear schedule for the improvement, tight at the start, maybe as short as a week but no longer than a month and then get longer as the program becomes more developed.

Electrical Safety Program - Introduction

The introduction will cover a few sub-sections including:

Scope
Purpose
Definitions

Some ideas for coming up with electrical safety program scope and purpose here. Think about what your company does, and what the workers do on a daily, monthly, annual basis.

Over the next couple of weeks I will be adding more information about what should be included in these sections, and where I think the priorities should be for the development.

Other tools

Until you have the first couple of passes of the electrical safety program prepared, and there are clear stakeholders developed within the organization (it must include high level management and on the ground workers) I don't recommend veering into the realm of SAAS or business management tools. Use the tools that you have, but better still keep a live document where the team and stakeholders can work on it continuously.

For many companies this document and a folder with the various forms/permits and record will be enough.

Footnotes

[1]	Definition from the 2021 version of CSA Z462:21 Workplace electrical safety

PV Solar Development Process

2023-09-29T00:00:00-03:00

With any solar development there are two stages with a total of 7 phases. This concept is something that I came across in a presentation published in 2017 titled Dii Desert EnergyIPP Solar PV Project Development Roadmap. This presentation oulines 8 decison gates with one in the middle of the feasibility phase.

The two stages are:

FEED
EPCO

These are acronyms that are used often in industry and they stand for, front end engineering development and engineer, procure, construct and operate.

Below I will introduce these phases and how they should be considered to ensure a successful project. Each of these phases could be a series of books in their own right, so if there is one that you would like for me to elaborate more on, let me know.

Photo by Daniel McCullough

FEED Stage

With the feed stage there are three phases that flow into each other. they are:

Business Development
Feasibility Study
Contracts and Financial Close

The goal at this stage is to determine if there is a high liklihood of the project succeeding and if not to stop before continuing farther. This is especially true during the business development and feasibility phases. When these phases are completely correctly, the project definition, risks, opportunities, etc. are well documented and understood by all stakeholders.

In some cases the project won't make sense at this time however in the future those situations may change, and having a well documented project at this stage may allow the project to have more opportunity when the time comes.

For example, maybe the project is in a remote location and the capital cost of the equipment and transportation is too high, or the expected revenue opportunity is too low. You determine this during the start of the FEED stage, but something changes in 2-3y time. This could be a government annoucement of a wharf upgrade, or a new rail line. It could be that the town is increasing its EV fleet and there is a need for more local generation. etc.

Let's take a look closer at these phases.

Business Development

The business development phase includes defining the project, if its an existing organization developing the project this will include aligning with the existing company vision, mission, etc and if its a new orgnaization developing them.

It also includes the project opportunity identification and site or sites identification, because without the suitable site there can be no project.

The Importance of the Site

Like other variable non-carbon emitting generation, site is critical. Solar is no different.

You will want to have a site that is close to the demand, relatively flat and sloped in a way that will maximize the generation of useful energy. This does not necessarily mean the maximum generation, you want to make sure that the cost of production is minimized and in some cases that may mean that the panels should be orientated in a way that isn't optimal for MWh/MW ratio over an annual period.

Depending on the permitting requirements the land may be able to be cut and filled to meet the generator demands, but in other cases the land may need to be left as is.

It really is critical to have the site of the project identified and secured as early in the process as possible. At the business development stage securing rights to the site may not be critical, but having a path of understanding the stakeholders/owners of the identified sites is critical.

It is much better to spend some time during the business development phase talking to some land owners, or engaging a site aquisition expert to do some exploratory site identification to ensure that there is enough available land for the identified project.

Photo by Markus Spiske

Feasibility Study

The feasibility study is something that includes most of the front end project development. In fact, Mr. Fadi Maalouf (the author of the earlier mentioned presentation) recommends including a full pre-feasibility study phase and having a decision gate there, and I agree.

However, for smaller projects (<5MWdc or so) this doesn't always make sense. Instead I recommend that the person who owns the Feasibility Study on behalf of the stakeholders develop it in a way that allows three different stopping points:

Issued for Review
Issued for Approval
Issued for Financial

These would represent 30% complete, 60-75% complete and complete respectively. If you follow this process, I recommend that the decision gate be placed at the Issued for Approval document as this will have enough of the information to decide if the project is a go/no-go.

The chapters of this report should include:

Conceptual Design
Cost Plan
Energy Yield
Energy Tariff
Licensing and Permitting Roadmap
High-Level Project Schedule
Risk Register
Financial Model

These are too many to go into detail in a single article, but the goal of this phase is to determine if the project can fullfil the business needs outlined in the business development phase, within an acceptable liklihood of success.

As I mentioned above, it is better to learn now that there isn't a path for the project to succeed earlier in the process.

A couple things that may be identified during this phase that would result in the stopping of the project may be:

An unclear permitting Roadmap
not enough energy potential on the site to meet the project needs
too high financial, land, procurement risks
etc

Photo by Dimitri Karastelev

Contracts and Financial Close

Once the project is through the decision gate after the feasibility study it is time to get the rest of the partners together that will take the project through to the operations phase of the project.

Some of the contracts that will need to be signed by the end of this phase include:

Land leases
Power Purchase Agreement (PPA)
Major Vendor supplies
Engineer, procure, construct firm (EPC)
Grid Interconnection Agreement
Project Insurances
Legal Adisors
Financing Agreements
etc

There are a lot of documents that need to be put together and signed in a particular order to ensure success at this stage. It is not hard to have extended timelines because of the various interdependancies of some of these contracts.

The technical side

During this phase of the project there is a lot of negotiating, contracts, and financial modelling. None of those things are things that I'm an expert in.

The parts that JMK does assist with is the negotiations with the utility for the PPA, and grid interconnection agreement, development of the scope of work (SOW) for the various contracts from detailed design through to operations, and identifying any gaps that may exist early in this process.

JMK also advises on different contracting strategies from having an EPC complete everything, to assisting with a design-bid-build approach; and everything in between.

Closing

I think that's enough for this article. It started to get away from me.

There are still four phases to a successful project and I will make sure that I have that article published next week.

Have you ordered your equipment yet?

2023-01-25T00:00:00-04:00

It is the end of January, and depending on your project it may be already too late to construct that project this year. If you are reading this and thinking that, well its different "here", I'm here to say, "have you talked to your suppliers lately?".

The reason is that I have current projects/clients in 4 US states, 3 Canadian provinces and one in the EU, and the typical lead time has increased from 10% to 200% from what I would expect. Switchgear and transformers are the typically the worse than some active components like PV inverters, but just one of these items will drive the critical path.

For example, in September I received a quote for padmount transformers that was 40weeks from the fastest (assuming an order qty of 10), up to 110wks from another vendor. Today that "fast" suppliers times have increased, but the top end is softening a bit.

For switchboards and switchgear there is a range from vendors not taking orders, at least one off orders, to 30weeks.

Even with the optimistic looking 30wks this will put projects that need to be online in this calendar (or fiscal) year at risk if they haven't been purchased yet.

There may be options

If you have a project that is scheduled to be completed this year, and what you have read above scares you, there may be options.

Schedule a call with me if you would like to discuss your project and see how I can help make sure it is a success; it may take making decisions earlier than you typically do, but I can help you walk through those procurement hurdles.

PV Solar Angles

2022-08-10T00:00:00-03:00

Solar panels are most effective when the solar rays are perpendicular to the panel service. That's the first angle that matters, getting the panel pointing the right direction take a little bit of math.

The vast majority of the time you will use software that does this automatically, but doing a few by hand to understand what the software is doing is very helpful in getting a basic understanding of what's going on.

So, what angles matter?

Sketch showing declination angle

First angle we need to determine is the angle of declination (δ), this is the angle between the earth axis and the solar plane. It varies over the year and is calculated as:

δ = 23.5*sin((360(284 + d))/(365))

where:

d = day of the year

With δ calculated we can calculate the elevation angle α, this is the angle that the sun hits the earth during peak hours, solar noon.

Sketch showing elevation angle

α = ϕ + δ

where:

ϕ = latitude

Because the highest irradience is at solar noon, for static systems we want to ensure that the panel is perpendicular to the sun at that time, that is where the elevation angle β comes in.

Sketch showing the tilt angle

β = 90 − α

Sketch showing how the tilt angle is calculated

β will always vary between 0 and 90 degrees, 90 closer to the poles and 0 at the equater.

Next Steps

Once we have a handle of the various angles involved we need to start defining the various solar radiation and how it will determine the solar energy converted to electrical energy.

From there we can determine the optimal angle β for the panels, and how changing that angle will affect energy production.

PV Solar Design Introduction

2022-07-12T00:00:00-03:00

There are approaching 130,000 solar installations in the USA alone, and while that number isn't growing as quickly as it was in the 2010s, other regions such as India are picking up the slack.

Source: SEIA U.S. Solar Market Insight Q2 2022

Solar accounts for 4% of the total electrical energy consumed in the US which is a small, but growing number. That is 80x what it was in 2012. [1]

An even more interesting statistic is that for the last 4 years solar has accounted for the highest percentage of capacity additions to the US grid. 50% of all new capacity added in Q1 of 2022 was Solar. [2] That is a huge number.

Source: SEIA U.S. Solar Market Insight Q2 2022

I haven't been able to find great statistics on this, but I'm assuming that the vast majority of these installations have been Photovoltatic Solar, also known as PV. However when we talk about solar there are two other types:

Concentrator Photovoltaic (CPV)
Concentrated Solar Power (CSP)

Concentrator Photovoltatic

Conentrator Photovoltaic (CPV) is very similar to the PV in that it uses the same physical process to convert photons into electricity, however it does this by concentrating the sunlight into a very small, and efficient multi-junction solar cell using lenses or mirrors.

To help keep the efficiency as high as possible these arrays are typically installed on dual axis trackers to point the array directly as the sun.

Concentrated Solar Power

Concentrated Solar Power (CSP) is completely different from CPV or PV, in fact the only thing that is the same is that it uses the sun for energy.

CSP works by directing the solar energy into a point (or a series of points) to heat a liquid (or a solid to a liquid) and then this liquid is used to heat water to convert it to steam. This steam is converted to electrical energy using similar thermal turbines as coal, oil, etc.

CSP sites are up to 50% efficient, however they require specific sites to set up and work.

The Ivanpah Solar Power Facility, image by Doc Searls

The Ivanpah Solar Power Facility is a 392MW CSP that is expected to produce 940,000 MWH per year. [3]

Photovoltaic Solar

Finally we get to photovoltaic (PV) solar, which is the one that the rest of the series will be concentrating on. The reason that PV solar is so popular is that it attacks the problem in a simplier way, its a hammer for every nail.

CPV is great if you only have a small area and need to have reliable energy in in a disconnected site. For the same panel area you can extract much more energy than with PV. A CPV system can have an efficiency of 44%, where typical PV cells, at cool temperatures, are half that at 22%.

CSP is a different beast where it can only be installed in very specific sites.

PV may have a lower efficiency, but it can be installed almost anywhere, it is a lot cheaper and lighter than CPV, and there is competition in almost every market in around the world. If you want to have a little more system efficiency you can add trackers, dual or single, and since the panels are much lighter you can add a lot more to them for cheaper.

They can be of almost any size, from the small ones in your calculator, to any array that is 100s of MW.

Why Solar?

Why not?

That's not a great answer, but here it is. I don't think that solar is going to be the holy grail that a lot of people think, at least in the next 50y, however it is a very powerful tool to help reduce our reliance on carbon emitting fuel sources.

It is also a technology that allows people to feel like they are part of the solution by installing panels at home and work. That may lead to support to the policy decisions that need to be made at a government level to make the fixes we need.

The next few articles will be covering how solar system design happens, what you need to know etc.

I'm sure after that I will have a few articles about why solar is going to cause a lot of challenges to the operation of the utility grid over the next decade and some of the things that we, as a society, will need to figure out to make everything work.

I don't think the answer is "microgrids", but rather more transmission, something that is harder than an apartment building in a 60s era suburb, but it is the solution if we want variable energy sources as our main electricity source.

Conclusion

This was a short introduction to solar design and the various types of solar systems. From this point we will be covering PV Solar, but if you would like me to cover CSP or CPV in more detail let me know on twitter and I will add it to the calendar.

Sources

[1]	SEIA Solar Data Cheat Sheet (Online). Available: https://www.seia.org/research-resources/solar-data-cheat-sheet [Accessed July 12, 2022].

[2]	SEIA U.S. Solar Market Insight (Online). Available: https://www.seia.org/us-solar-market-insight [Accessed July 12, 2022].

[3]	US DOE Loan program Site (Online). Available: https://www.energy.gov/lpo/ivanpah [Accessed July 12, 2022].

ClickPLC Modbus TCP and VTScada

2022-01-25T00:00:00-04:00

This is the first in a potential series called Tutorial Tuesday where I post a quick tutorial on some technical task that you may be working on. If there is a tutorial that you would like me to put together let me know on twitter @jmkengineering.

This tutorial topic comes from the need to get some VTScada data from my local home energy management system into my ClickPLC that is controling the thermal ETS. Rather than adding all this information into a massive post there, I thought that it would make more sense to have its own article.

Setting up the ClickPLC

The first thing we need to do is set up the PLC.

1 Enable Modbus TCP Server

We want to make sure that Modbus TCP Server is enabled, take note of the TCP port number, you will need that when setting up the Port and Driver in VTScada.

2 Setup Send Communication Block

Next you will create a Communication Send block.

This block will SEND data from the PLC to the VTScada application.

If you want a "fuller" understanding of all the fields Automation Direct has a detailed page on the send instruction for Modbus TCP on their website.

3 Setup Receive Communication Block

This is exactly like the send above and looks like this.

And like the send, Automation Direct has a help page for the Receive Instruction: Modbus TCP too.

Configuring VTScada

If you have configured any Modbus device on VTScada this will be exactly like those. For this example I will just show the highlights without going into details. [1]

1 Configure the Port and Driver

This is straight forward, first the TCP port:

Make sure that the IP address matches the PLC.

Then the Modbus Driver.

The only thing you have to make sure of is that the driver is set for Open Modbus TCP.

2 Configure the test I/O tags

I created two tags to test, one status and a control. [2]

2a The Status Test Tag

First the status tag:

For this test lets assume that two positive digits with a single decimal. To make this work we modify the scaled and unscaled values:

2b The Control Test Tag

The Analog Control tag is very much the same, but this will be tied to an existing tag, the studio temperature. It is, afterall, the reason why I need to put this together.

And then set the scaling 100->1000 so that we can get a decimal in the PLC.

3 Did it work?

Yes, here are the values in VTScada

The Last Bits

[1]	I'm using VTScada version 11 at home. Its old, but it works and I don't upgrade production equipment without strong justification. I may have to write an article just on that topic at somepoint.

[2]	VTScada has an option to allow writing with status tags, but it didn't work the first time and I don't have time to troubleshoot today, maybe another future article.

Updating the program - Home Energy Management System

2022-01-24T00:00:00-04:00

Back in the fall I finally started programming the ClickPLC to manage the thermal ETS that heats the studio.

There were a couple things that I just didn't bother dealing with:

adding space temperature
finer control during long periods of low prices (weekends)

The simple reason is that I didn't have an analog temperature probe that I could easily add to the PLC and I didn't want to get into using MODBUS. For the time being I added a manual ON/OFF switch and a AUTO/ON switch.

This way I was able turn off the heater during the weekend, go back down and turn it back on on Sunday afternoon and everything would be great. However, when I came down this morning it was 16C in the studio, I forgot to TURN IT BACK ON!

So, I have it ON manually so that I don't freeze this morning, but it is the kick that I need to update this.

The Plan for today

I still don't have a temperature sensor, but I want to make sure that I give the ETS enough time to charge on Sunday and keep the space warm. The way that I want to do this is based on the room temp, if it is below 19C I want to make sure the ETS is on, during low power, and then off around 22C.

22C is about where I have the dial on the ETS set, which is something that I need to fix but it requires running another control wire.

What will the logic look like?

I'm starting with an expensive clock controller that takes no account of the temperature inside or out.

My first thought was something like this

This will work for the outside temperature, but "already warm" doesn't know the day of the week by itself. I will need to add timer to that one.

I'm thinking 4h is a good time to get started, and the way that ClickPLC works, when it's enabled the timer starts and stops when the enable is gone. The T1 only changes state when the timer gets to the setpoint.

So the "final" logic will look something like this.

Getting this into the PLC

The first thing that I need to do is get both inside and outside temperature into the PLC. Since I don't have these connected directly into the PLC, I need to get them from VTScada.

Modbus is the "easiest" way to do this, but this post has gotten long enough.

Stay tuned, that post is coming.

Finally programming my ETS

2021-11-25T07:02:00-04:00

All of last year I had to use alligator clips to "switch on" the heating elements in the ETS. Lift off the programmable thermostat and clip them on.

Last week I decided that its time to update the way I get the data from the energy monitor into VTScada, and bought a relay at the same time. Why I didn't do this any other time in the last 18months is beyond me. While that is in shipping I've started the programming in the ClickPLC I have on the wall.

The program modifications

I upgraded the firmware to version 3.20 (it was in the early 2s before) and started digging around to see what information is built in to make this work.

Before I get into the weeds, lets talk about what this little routine needs to do.

We only ever want to "charge" the ETS during the cheap rates. I'm not going to set this up such that it accounts for weekends or holidays differently, it will only account for the nightly rates, from 11pm to 6am. So basically, it will energize an output whenever the time is between 23h and 6h.

I'm writing this after 5pm, or 17h, and that is the value when I check the data view while I'm online.

Now to layout the ladder logic

Checking/Commissioning

I don't have the relay, yet, but I can play around to see if its going to work. First, after I load it into the PLC here are the new values. First I need to over ride (OVR) the X001 bit, then lets see how the program runs.

Nothing happens, as expected. It is still 5pm and 17 is bigger than 6 and isn't 23. Now, what happens when I change 6 -> 20, will it energize the output?

But I still want to test it to make sure that I can get the lights to come on, so I will change the first argument to be 20 instead of 6 and SUCCESS

Next Steps

Now I just need to get the relay and connect everything up.

I had a single relay in the house that I broke before even starting the testing, so I should have a couple new finder relays at my mail box later today, and I will connect it this weekend.

Then when that is working I will re-wire the existing programmable thermostat to control the fan in the ETS to control the temperature in the room.

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Stay tuned

Answering the Question: What is a Smart Grid?

2021-11-25T00:00:00-04:00

The North American power grid is an incredible thing. Stretching from coast to coast, through mountains and forests and valleys, it is a massive network of power plants and transmission lines that deliver electricity to homes and businesses across the continent.

And it's old.

In the last couple of years, when talking about power grids, you may have heard a new term thrown around: "smart grid".

"The smart grid is the future of power generation."

"The smart grid is the future of energy management."

"We need smart grids to implement renewables and reduce carbon emissions."

So clearly, smart grids do a lot. However, what does the term "smart grid" really mean? If you look up "smart grid", you'll find that smart grids can do a lot of different things. From IEEE:

What is the Smart Grid?

Smart Grid deployment is imperative, not just in the United States but around the globe. But the smart grid is a revolutionary undertaking—entailing new communications-and-control capabilities, energy sources, generation models and adherence to cross-jurisdictional regulatory structures. Successful rollout will demand objective collaboration, integration, and interoperability among a phenomenal array of disciplines, including computational and communications control systems for generation, transmission, distribution, customer, operations, markets and service provider."

That's all well and good, but it doesn't actually tell us what a smart grid is: it just gives us some vague notions about what needs to be done for a smart grid to be deployed.

"A smart grid is an evolved grid system that manages electricity demand in a sustainable, reliable and economic manner, built on advanced infrastructure and tuned to facilitate the integration of all involved."

This definition tells us what a smart grid is, but it still leaves more questions than it answers. Maybe we aren't asking the right question. Instead of asking, "What is a Smart Grid?", maybe we should be asking "What makes a grid smart?"

Smartgrids.gov has an answer to this question: "In short, the digital technology that allows for two-way communication between the utility and its customers, and the sensing along the transmission lines is what makes the grid smart. Like the Internet, the Smart Grid will consist of controls, computers, automation, and new technologies and equipment working together, but in this case, these technologies will work with the electrical grid to respond digitally to our quickly changing electric demand."

So the "smart" in smart grid has to do with how the grid handles communication and power control. Here's my list of what I believe to be a "smart grid".

A Smart Grid Monitors and Gathers Data About All Loads and Supplies

Smart grids monitor and gather data using smart metering technologies. For example, a home connected to the smart grid could be communicating with the utility via smart monitors such as the Neurio. This data can be used by the consumer to reduce their electricity demand (by not using electricity during peak power generating hours). Even better is if the monitor communicates directly with the utility, allowing the utility to cut the power to certain circuits in the home when necessary (think not being able to run your clothes washer, your dryer, your dishwasher, and your air conditioning all at the same time during peak power cost hours).

A Smart Grid Uses Gathered Data to Optimize Energy Generation

Optimal energy generation can mean different things depending on who you are talking to. For most people, optimal energy generation means producing as much energy as needed for the lowest cost. Traditionally this has been done with coal and gas fired plants, but smart grids can better use a combination of energy storage, renewables, and fossil fuels to achieve this goal. Let's be honest here: fossil fuels are never going away. Fossil fuels have one advantage that current renewables cannot match: on demand generation. When you need power, you burn more fuel. What a smart grid can do is crunch the numbers to reduce fossil fuel consumption. Since the smart grid is collecting all the data from the loads attached to the grid and the generation sources supplying the grid, it can determine when to use which resource when. For example, let's say you have a system with a far away coal fired plant, and closer solar, hydro, and wind resources attached to batteries. The smart grid will attempt to use 100% of these renewable resources (storing whatever it doesn't need at the moment in batteries), and will have a schedule for bringing on power from the coal fired electricity based on :

The load profile of the whole system.
The generation profile of each electricity source.
The cost of burning fuel and transmitting that fuel powered energy across long distances.

And it'll do all of this automatically.

The Smart Grid is Predominantly Made Up of Distributed Generation Sources

Right now the power grid is heavily centralized: large, expensive power plants in urban and industrial centers generate power and distribute it hundreds of kilometers (or miles) away from the source along large networks of transmission lines. The smart grid is all about distributed generation. This distributed generation is a result of two big things:

Improved communications and controls that you get with the data monitoring and optimization that I talked about above.
Improved efficiency and widespread adoption of renewable energy resources.

It makes sense for loads to be close to their supplies, but you can't just build renewables wherever you like. Solar panels need enough sun, windmills need enough wind, hydro needs access to a river or dam, tidal needs to be on the coast, and geothermal needs a massive underground heat source. These of course have to be combined with smaller fuel based power plants for times when extra energy is needed on demand (since energy storage technology isn't good enough yet to forgo fossil fuels entirely). All of this means that integrating renewables with the grid causes generation to be distributed more widely. These distributed sources won't have as much capacity individually, but combined can match large, centralized power plants. There are two big upshots here:

All of the renewables being used reduce fuel consumption and carbon emissions.
More distributed generation sources means electricity doesn't have to travel as far, reducing transportation costs.

In short, more distributed generation with efficient renewable usage reduces power costs.

The Smart Grid Reacts Faster and is More Reliable than the Traditional Grid

Because the smart grid is constantly gathering data and monitoring the power system, it can react fast to any instability or service interruptions. Because there is so much distributed generation and the grid is optimizing supply usage, there are many available power sources that loads can be shifted to. If there is a problem with one supply, loads can be shifted to another supply to maintain service.

Summary

To sum it up, smart grids do four key things better than the traditional power grid:

The smart grid monitors and gathers more data than the traditional grid.
The smart grid has better control and optimization of energy resources than the traditional grid.
The smart grid has more distributed generation than the traditional grid.
The smart grid is faster and more reliable when faced with abnormalities than the traditional grid.

Hopefully now you know a little more about smart grids! If you have any questions, feel free to shoot me an email at cole@jmkengineering.com. Even better, sign up for our newsletter! Every week, we provide all sorts of cool information about power systems and electrical safety. We might even answer questions you didn't know you had! As always, thanks for reading!

EthernetIP and the SEL RTAC - Tutorial

2021-07-09T11:59:00-03:00

My experience with EthernetIP and CIP was limited to the interaction between VTSCADA and Allen-Bradley PLCs. This experience was amazingly straightforward. The CIP driver built into VTSCADA made me complacent and I assumed that it was going to be just as easy when I got started with it in the SEL-RTAC.

It wasn't

The goal of this tutorial is to get you started with the installation and understanding how it works and how I got it working with a little help from SEL support (thanks Landon).

The goal

The project I needed this for was originally designed to communicate PLC-to-PLC over EthernetIP, however at some point the utility decided that they wanted to change this to DNP after the site was commissioned and running for a year.

Enter the RTAC

SEL released a module/option for EthernetIP with the RTAC right around the same time as this requirement came up, so we purchased a SEL RTAC-3505 to do the work. It will communicate with the PLC and relay that information to the Utility RTAC.

There are approximately 12 digital status back and forth and a handful of floats.

Lets Get started

First we need to get the device into the project.

When you add the device, and give it a name this is the default starting settings

The first thing you will need to change are the highlighted settings. The "allow anonymous clients" is optional for Allen Bradley PLCs, but the explicit message feature is NOT

Next we need to create four Assemblies, two for the digital IO and two for the analog IO.

It's important to group the datatypes, in this example the binary points will be communicated as SINT and the analog as REAL. The outputs FROM the PLC will need to be read-write and the inputs read-only.

At this point you will want to save the configuration the names and access control will be dependant on the next step.

We need two I/O connections, one for SINT (binary) and one for REAL (analog)

These define the connections in the Allen-Bradley software and where they are written/read in the RTAC.

Configuring the IO tags and points

When you created the four assemblies, four tag lists were created. They can be accessed by clicking the "+" for the drop down.

From there you will create the various tags that will need to be configured in the PLC, the binary points will be configured with a SINT data type, this is a 8-bit interger that we will break out into BOOLS in the PLC and tag processor to communicate individual bits.

For this example I will create two for both binary inputs and outputs.

Do the same for the analog lists, and ensure that the data type is REAL

In practice I don't typically change the tag name or tag alias for these types of communication. If they aren't being used in custom logic in the RTAC itself there isn't a need for it to be human readable after the configuration is complete.

To ensure that the IO mapping can be read and troublshoot-ed I add comments in the tag processor.

Exporting the EDS File

At this point I recommend ensuring there are plenty of spare tags if it was a live project because when you register it into the Allen Bradley database, if you make any changes to the structure or number of tags it will need to be re-registered.

In this tutorial I won't cover the allen-bradley portion of the work. This is completed in RS Linx or Studio5000, which you may not have access to. Or you may be working with an automation team that is external, and all they need is to add this RTAC to their database to map the information.

To do that, you export the EDS file and send it.

Now that you have a complete configuration, you can export the EDS file for the automation group, or to load into the PLC program manually. When you initially go online with the RTAC this will automatically be created.

Save the file in the project folder and now you are ready to do the rest of the work in the RTAC in parallel with the PLC team.

Working in the Tag Processor

It is important to ensure that the Data Types match in the tag processor. For DNP the default binary status is an SPS type, but you can get access the BOOL portion by adding ".stval" to the tag.

The binary output from the PLC is SINT type, but to access it on the bit level "BOOL" you can add ".#" for the bit you are mapping.

This is also the place that I add those notes I mentioned above to ensure that the mapping b/w the PLC, RTAC and remote device all match. I add the "purpose" of the tag and communication path to the description column in the tag processor. I'm not sure why this column isn't included by default, but it is straightforward to add.

Right click on the header bar and select column chooser. From there a Customization box will come up and you can drag any column you would like added to the tag processor.

Then for analogs you do the same thing as the digitals, making sure that the data types match.

Now you are ready for testing on live equipment.

Closing

If you found this tutorial useful I would love to hear from you in the comments or a share on the various social media platforms.

I have more tutorials like this in the works, but getting access to physical hardware to test on is difficult. If there is a specific platform, hardware combination, etc that you would like me to test next please let me know by signing up to my newsletter and hitting reply to the first email that comes in.

Feasibility Studies for Renewable Projects

2020-10-06T07:44:00-03:00

There is a lot of activity around adding renewable projects to isolated system and/or behind the meter. Renewable generation development has matured a lot in the last 10 years, and solar has come down in price [1] to the point that the risk of installation is very low.

The yellow line is PV solar and the grey line is onshore wind. Its 2020 and PV Solar is on par with onshore wind for the first time on a kwh cost basis, below $0.05 USD/kwh. Offshore wind and CSP solar are dropping too but they are still closer to $0.1 USD/kwh, or double the price of PV and onshore wind.

Couple the high cost of energy in some markets with businesses with large cash reserves, developing behind-the-meter generation starts to be come very attractive.

Then there is the capital cost of storage predicted to be below $200 USD/kwh (for a 4h battery) by 2030, that is a 50% reduction from today.

Coupling PV solar with storage could meet a signifcant amount of on-site energy requirements, below market rates. But before you can know if there is a fit for your site, you need a feasibility study.

What is a feasibility study

A feasibility study, in general helps a business determine if something can be done, and start to understand the risks of doing (or not doing) that thing.

The Merriam-Webster definition is simply, "a study to show if something can be done", but I think for this type of project, Investopedia does a better job at the definition.

A feasibility study is an analysis that takes all of a project's relevant factors into account—including economic, technical, legal, and scheduling considerations—to ascertain the likelihood of completing the project successfully.

https://www.investopedia.com/terms/f/feasibility-study.asp

My role is typically to provide the technical and project management portions of the study, and provide inputs for the financial modelling and economic analysis.

Technical Analysis for a Feasibility Study

Before I even get started with the technical analysis for a behind-the-meter project, I like to work with the client to determine the constraints for the project. If they haven't thought about them yet, we workshop ideas until we agree on where the walls are for the project.

Some of the large items that we determine are things like.

How much energy do you want to dispatch?

Before even looking at the current load profile of the business I want to know how much of the energy they would like to displace. Are they aiming for a balance of lower cost self-generation and reliable utility connection? Or do they want to be net-zero so that they can generator 100% of their necessary energy?

To go further, do they want to be completely self-sufficient for periods of time, disconnecting from the grid completely. This is a microgrid type project.

We talk about these items even BEFORE we determine if there is a mechanism for selling/producing into the grid.

How much space do you have?

If this is a facility in a business park, there may be very limited amount of space to install PV cells let alone space for a wind turbine.

What is the timeline?

So, how fast do you want to deploy this project? If you want to go online within a year wind is out of the picture. Especially if it is going to be outside financed. The MET tower needs to be in the air longer than that just to understand the wind resource.

PV on the otherhand is much less capital intensive to get started, and if needed more can be easily added to the system. Install 1MW on year one and then another 500kW in year two and three, vs the upfront requirements of installing a single 2MW wind turbine.

Now lets look at the load

The first step for a project like this is to look at the load profile for the facility. Determine its shape, and "texture". What you are trying to answer is:

Is it balanced throughout the year?
Is it balanced throughout the week?
Is it flat or "spiky"?
etc

Then. depending on the answers and constraints to the project you can start digging in further. For example, if they want to reduce their utility load as much as practical, we want to see if there are ways to "shape" the load with the generation on site. This can be through automatic load shifting, manually through plant scheduling, etc.

To do this it is best to if the facility has a detailed energy management system broken into business or operating areas, with multiple years of historical 15min or better information.

As a side note, I wrote about this in a recent newsletter where I referenced a paper I was an author on titled "PLC BASED ENTERPRISE ENERGY MANAGEMENT SOLUTIONS" pdf here. I think its time that I update that paper with even easier to integrate solutions that have even more information. If that's something you would be interested in let me know in the comments or on twitter.

Lets Evaluate some Technology

When I have a good understanding of the load profile and the most that would be able to be shaped, I start to look at various technologies and methods to meet the constraints of the project.

If the project goal is to be a 100% self-reliant microgrid for periods extending into DAYS, with full production/operation, then that technology mix will very likely include lots of generation and storage solutions including:

the main renewable resource (PV, wind, hydro, etc)
backup power, likely diesel or gas
chemical storage (Li storage, lead-acid, etc)
active demand side management and load shedding scenarios
etc.

This is where I start some very preliminary models with various technology mixes. When I have narrowed the combinations to something reasonable, no more than 5 and no less than 3, its time to have the first presentation.

These scenarios will have preliminary capital cost estimations and risk matrices associated with them. For example, people still feel very strongly about large wind which may cause risk from stakeholder feedback. Or there may be schedule/financial risk on the global lithium or silicon market that affects the cost or delivery of solar and storage.

Refine, Refine, Refine

At this point the team will have alignment on the various technology mixes and its time to refine the models and complete preliminary front end engineering and design for the scenarios.

There is a balance to refine enough to increase the confidence in the end results, but not so much that a lot of energy has been expended on dead end options.

To manage this I work with the owners after every iteration to ensure that they agree with the paths and decisions that I am making before they even see the report.

Time for some Project Management

In parallel with the technical feasibility portion of the project its time to start identifying capital costs, timelines, project risks, etc for the identified scenarios.

This includes determining who the stakeholders are and if they are different for the various scenarios. Working with subject matter experts (SMEs) to determine permitting, testing, etc requirements for the options we are investigating.

I include detailed gantt charts and risk matrices with every study. They are easy to visualize the project and the critical path. In some cases the critical path for the project, and the risks that are out of the owners hand will determine the scenario chosen.

To pick on wind again, if there are onerous permitting requirements associated with wind, and the timelines are both long and not clear; then it may be prudent to chose an option that may have a higher levelized cost of energy (LCOE) but has a much lower set of risks.

Contrast to Isolated Systems

The process for isolated systems is very similar to behind-the-meter projects, the biggest different is integration and information from the system operator. If the project is placing a very large (compared to the system this could be 100kW) facility, the system operator will need to provide detailed information related to interconnection at the start of the project.

The other consideration when connecting to a system that you don't control is the power purchase agreement and the interconnection agreement (PPA and IA).

These agreements, and the path to obtaining these agreements, are an integral part of the feasibility study. If this type of project isn't something that has been done before, there may be large schedule and expense risks related to the interconnection that are out of the owners control.

How important is a Feasibility Study?

Well, its critical to the predictable success to any project. For small or simple projects they are likely just done in your head, or as part of a standard project approval project. So, even if the project folder doesn't contain a document titled "Feasibility Study: ..." that doesn't mean that the items identified in this article weren't considered.

Opportunity for BTM and Isolated System Projects

With the LCOE for PV solar and onshore wind below $0.05 and the cost of battery storage dropping, there has never been a better time to invest in renewable/storage projects.

Citations

[1]	Graph published by IRENA from an Article titled: How Falling Costs Make Renewables a Cost-effective Investment

Updating Heating Control - Home Micro Grid

2020-10-01T04:22:00-03:00

This post is all about how I'm updating the current control of the ETS that we installed last November.

When it was installed we had the contractor do the least control they could to get going, with the plan that I would upgrade it in the winter. Well COVID happened and that sucked up all my time, so now is the time.

What is an ETS

But first, what is an ETS? I wrote a short post about ETS devices here.

The coles notes version, is that an Electric Thermal Storage unit is a device that you can convert electricity into heat and then store it to be released later. This allows us to load shift to the night when our electricity prices are lower.

What's Installed Now

We have a Dimplex VFMQ 40 installed in the studio, this heats the entire studio in the winter. In the shoulder months it will heat the main floor too allowing us to minimize the heating in the rest of the house.

The contractor installed a programable thermostat that serves as a charge controller. To ensure that we charge the heater every night, regardless of the temperature of the room at 11pm when the rates decrease, we have it set for 28C starting at 11pm, 15C during the high rate time and 18C at the mid range time. This ensures that if it is extra cold out the heat will come on in the middle of the day when the rate is at the "normal" level.

The heat is released with a dial thermostat on the side of the unit that isn't exactly accurate.

Currently we heat the space to 24C during the evening and it "holds" for most of the day, and it will drop to around 19 and 20C by 6pm when I am leaving the office. This room temperature is based on the "dial" on the side of the heater. Its hard to dial in a specific, comfortable temperature.

Overlaying the power for the storage heater you can see how the current charge controller "charges" the bricks b/w 11pm and 7am.

There are a few things that I should be able to dial in with the new design, including limiting the swings. Ideally I would like to keep it b/w 22C and 18C, the snapshot above is b/w 24C and 17C.

What I want to have

The goal of this little project is to control the heater more efficiently and be able to modify the schedule from the Home Energy Management System.

As a starting point, I want to control the room temperature at 18C overnight, starting at 6pm in the evening, and then warm up to 21C during the day. The image above is from the members only video that will accompany this post.

I don't have temperature sensors that I can plug directly into the controller, so, I'm going to re-use the programmable thermostat to control the room temperature and the controller will ONLY control the charging cycle for this version of the controller.

The goal is to limit the saw toothing and conserve as much energy as possible.

Added benefit in the shoulder season

In the shoulder season there isn't as large of a heating requirement, and as such there isn't as much of a need to "store" more heat energy than is needed.

So, if I keep track of how long the heater charges for, I will know how much energy was needed the previous day. Couple that with an understanding of the deviation from the programmed temperature, for example, if the goal temp at 5pm is 20C, and it dropped to 18C, or if at 10:50pm the temp is more than 1C from the goal temp, we can assume that the "tank is empty".

But if the previous day didn't use all the charge time AND the temperature at 10:50pm is above or at the goal temperature, then we can "just" charge the difference rather than over charge.

This is for the programming side, which I haven't finished yet. First the hardware control.

The Control Circuit Now

The control circuit looks like this :

K1 is the charge controller, this is a programmable thermostat today. I will be re-using the thermostat for room temperature control, replacing the dial.

It is mounted next to the heater itself, so I will have to move it closer to the desks to have the desirable affect.

RTR is the room temperature controller. This is a dial on the heater today. This will be replaced with the thermostat when I replace the charge controller.

First Step: Hardware Design

I'm planning to use the ClickPLC as the controller for this part of the project, and will be adding everything to the VTScada application that I have monitoring the energy use at the house and studio.

The new additions to the control circuit as it stands today include:

Replacing the thermostat with a relay that will be energized from an output on the PLC. I was initially hoping that the PLC would be able to drive the contactor in the heater directly, it is 24Vdc rated, but looking at the thermostat I don't think so.

The thermostat has a rating of 1A, where the PLC has a rating of 0.1A.

Oh yeah, and one is AC and the other is DC. So a relay is definitely going to be needed, but it doesn't have to be a big one like I assumed in the video.

I won't be buying the new relay until I have the software started, and that is what I will be writing about next.

Also I have finally added the CTs to the generator panel and that means I can start sizing my emergency storage solution.

https://twitter.com/jmkengineering/status/1309207970698481668

The load appears too small for what I was expecting, so I will have to do some investigating before I start planning how big the battery needs to be.

https://twitter.com/jmkengineering/status/1309211345787727874

Looking for your help

And on that subject, if you know a company like BigBattery (but in Canada) who puts together systems like this one, let me know. This may be just what I need for my battery generator project as part of the home microgrid.

If you know of a supplier in Canada, let me know in the comments (if you're a member) or email at jeffmackinnon@jmkengineering.com

Electric Thermal Storage

2020-09-29T15:15:00-03:00

There is a lot of talk about chemical based energy storage (batteries), but before batteries there was thermal storage.

Thermal storage is similar to using bricks or water for thermal mass, it limits the thermal swings by slowly releasing the thermal energy into the space even after the heat source (sun, fire, etc) has gone away.

Electric Thermal Storage (ETS) operates in a similar way. The ETS that we have installed in the studio used bricks to store the heat. When there is a call for heat in the space a fan draws air over the bricks "wicking" away the heat and releasing it in the space.

I'm not a mechanical engineer, so don't quote me on these terms.

Current Electric Thermal Research

There is still a lot of development in ETS technology, even with the attention to battery storage.

Most of the products we see on the market today, that are ready to buy still use thermal mass storage, but there is really neat chemical storage options being developed, like from Neo Thermal where they store the heat in a salt, similar to the heating pads you put in gloves to keep your hands warm.

Other Research in ETS

I did a quick search for "thermal storage" on IEEExplore and saw a few really interesting papers, including a couple that looked at using chilled water for "cooling" storage in commercial buildings [1]. This was an old paper, but thinking about it, with the AC load in California lining up with solar power, this may be a great place to dump excess generation from wind or solar installations.

Building on that old paper is this one from 2016 - Use of Adaptive Thermal Storage System as Smart Load for Voltage Control and Demand Response. [2]

In this paper they propose that a large scale ice thermal storage system, similar to the 1985 paper, could be used as part of a demand side management scheme for fast voltage control and load shaving.

Another paper spoke to the point that concrete waste from building demolition has a use as the thermal storage medium. [3] The specific heat measured in this paper ranged from 700 and 850 J/K*kg.

For comparison, the 176kg ETS that we have installed in the studio stores 32kWh and uses clay bricks that have a specific heat value b/w 900 and 1000 J/K*kg. [4] This recycled material may not be the best solution for small commercial applications, but possibly a solution for large industrial applications where there is more space and possibly a lot more waste heat.

So what?

If we are going to reduce our carbon emitions fast enough to limit the climate crisis to BAD, rather than great filter, then we will need to develop all the tools in parallel. There isn't a silver bullet.

While chemical storage in batteries is one great way to electrify everything, thermal storage is a great tool for building energy management and helping the shift to distribute energy resources (DERS) like solar everywhere, and wind.

This is something that I put together in an afternoon of reading, imagine the possibilities if you spent your masters, or made engineering thermal storage solutions a winter project.

Citations

[1]	D.R. Laybourn and V.A. Baclawski, "The Benefits of Thermal Energy Storage for Cooling Commercial Buildings," in IEEE Power Engineering Review, vol. PER-5, no. 9, pp. 31-32, Sept. 1985, doi: 10.1109/MPER.1985.5526437.

[2]	Luo, C. K. Lee, W. M. Ng, S. Yan, B. Chaudhuri and S. Y. R. Hui, "Use of Adaptive Thermal Storage System as Smart Load for Voltage Control and Demand Response," in IEEE Transactions on Smart Grid, vol. 8, no. 3, pp. 1231-1241, May 2017, doi: 10.1109/TSG.2015.2513743.

[3]	J.B. Martinkauppi, T. Syrjälä, A. Mäkiranta and E. Hiltunen, "Some Aspects of Recycling Concrete Crush for Thermal Heat Storage" 2018 7th International Conference on Renewable Energy Research and Applications (ICRERA), Paris, 2018, pp. 707-710, doi: 10.1109/ICRERA.2018.8566981.

[4]	https://www.engineeringtoolbox.com/specific-heat-solids-d_154.html

What is the Point of Common Coupling

2020-08-25T05:52:00-03:00

I have been working with a couple regulated utilities over the last few years. Neither of these utilities have a lot of small independent power producers (IPPs). There may be a couple of edge cases, or medium sized wind farms, but as a rule they generate all the energy they need.

The grid is getting smarter

However, the times they are a changing, and while I was working on the mini-hydro project in Labrador I recognized that in some cases understanding the requirements at the point of common coupling (POCC) can determine how a project is going to develop.

A lot of the time it is way more interesting to put energy into the civil and mechanical aspects of a new project, we are building big things even if ther are small, but how the POCC is going to be controlled can determine a lot of what needs to be completed within the IPP facility.

This is where an interconnection agreement comes in. The role of the interconnection agreement is to ensure that the IPP is producing power in a way that doesn't impact the customer power quality. It will have the limits of operation, how to synchronize, how the utility communicates that it can accept the energy, when the IPP has to be isolated at the POCC, etc.

There is a lot of protection and controls design that needed at the POCC. Settings need to be developed that will allow the system to synchronize to the utility, trip when there is a fault on either side, if the IPP can't accept the entire load, ensure that it trips if the frequency dips, etc.

Without a detailed interconnection agreement the IPP risks not having the proper protection elements in place when it comes time to start operations and producing power. Then what happens?

The general requirements for interconnection protection are typically straightforward, they always include:

Over/Under Frequency Protection,
Over/Under Voltage Protection,
Sync Check across the protective device before energizing and
Overload and overcurrent protection in both directions.

The timing and details of these protection elements is where all the time is spent. The interconnection agreement will include a description of HOW the IPP resource will be deployed locally.

Is it an energy resource?
Is it a inertia resource?
Is it a reserve power resource?
etc...

If the resource is going to be a source of short circuit current during a fault on the system, then it shouldn't have an instantaneous trip set too high such that it removes that short circuit current.

If the system is relatively "weak" in that area and a large motor starting drops the voltage for a short period of time it would be a bad time for the new generation to disconnect on low voltage.

Standardizing Interconnection P&C Design

We've started developing a standardized interconnection panel that includes all the necessary protection elements, SCADA connections, data concentration, etc. A system that allows IPPs and renewable resource developers to focus on areas that they are stronger in.

The system is still in preliminary design, and version one will include the following:

RTU/SCADA data concentrater to have all devices on site communicating to a single point
Multipurpose protection elements for MOST scenarios
GUI protection configuration
Cellular Network router/gateway

Including the technical abilities, it will include a full set of relay protection test sheets that will allow you to verify that the protection settings that you added do what they should.

If you are interested in a product like this and would like to help steer its feature set, send me an email at jeffmackinnon@jmkengineering.com

Voltage Levels and Terms

2020-07-02T07:39:00-03:00

The purpose of this post is to define the terms that I use elsewhere on this site, including documents, articles, tutorials, etc.

If you ask most electrical engineers what's low voltage, or high voltage you are not likely to get a straight answer. There are a lot of good reasons for this, Colin over at Newae he would consider 120V high-voltage, but for me, that's definitely low voltage.

If you ask an electrical safety specialist, they may define 30V and under low voltage because it is only then that the risk of shock is low enough not to consider the circuit energized.

My Voltage Level Definition

These days I'm mostly a P&C engineer with some SCADA added for good measure. I define voltage levels as follows:

Below 750V - Low Voltage
Between 750V and 25kV - Medium Voltage
Over 25kV - High Voltage

I do extremely limited design above 25kV so I don't define anything above there, however at the transmission level extra-high and ultra-high voltage terminology is used.

And this is the challenge with terms like medium voltage, or low voltage, its relative. Unless you know the background of your audience, its electrical jargon.

My Definitions

A mentor told me that the reason that there are definitions at the start of every report he wrote was to ensure that everyone was using the same language when they read the report.

Now when I reference low voltage, or medium voltage, you can refer back to this page (I will probably link it too) so you know what I'm talking about.

Password Override Jumper on RTAC 3505

2020-06-25T10:00:00-03:00

Have you ever arrived at a site and there is no password for the device? You have to log on the PLC or RTU but the owner doesn't know the password and it isn't written down anywhere?

Or maybe you have a bench unit that you forgot the password for. That's what happened to me this week. I finally got around to upgrading the firmware on my RTAC 3505 but I forgot the password.

Luckily SEL knows that this happens and they have a work around, assuming you have physical access to the device. There is a jumper for that.

First download the instruction manual

In case your device is different from the one that I'm working with, make sure that you download the instruction manual.

Why this is a secure method

The reason the jumper method works is that you have to have physical access to the device. This is not something that you can "remote" into it and lock out everyone, you have to be able to power it down, remove it from where its mounted, open the device, add the jumper and then power it back on before changing the passwords.

If this is a critical facility, you will have your first indication that something is wrong when the device is offline, and you can go and check what's happening. If you believe the device has been tampered with, you can take your backup settings and re-upload to the last known settings and be back running with a secure system.

Open the RTAC

Opening the RTAC 3505 is four screws, then you tilt/slide towards the end of the RTAC with the serial ports.

Add the Jumper

Once open you find the JMP terminal strip. If you are old like me you remember the jumpers on IDE harddrives, its the same style here.

SEL even includes a couple of Jumpers, one for the factory reset and the other for password override.

Install the password override jumper, in this case its JMP3, and then power up and log in.

Connect to RTAC with default username

I used the USB connection and when you get to the log-in screen the default username is "Edison" without a password. Now you can update the users with new passwords, remembering to add them to your password manager (I use 1password) so you don't have to go through this again.

And change the password.

Put everything back together

Then its a matter of removing the password again and placing the device back in service, or in my case upgrading the firmware.

15min for the entire process

This entire process takes no more than 15min and that is pretty awesome for a secure way to reset access information in the event of a failure in IT procedures.

Closing

If you like posts like this be sure to share on Linkedin or Twitter.

Time of Day Calculations with VTScada

2020-06-16T10:34:00-03:00

Someday I hope that it will be standard for utilities to provide a API that customers can use to calculate the current rates for energy, etc. Today however, we have to do it by hand.

My last post was a straightforward energy rate with a base charge, but I have a time of day rate at the house, so my rate is dependent on the month, day, hour and whether or not its a holiday.

This solution uses some advanced scripting.

Note, this is my first pass, I am actually testing to make sure it works as I write this. Also, I wasn't consistent with my thinking, but it works. If you have suggestions on how to clean it up, please let me know in the comments at the end.

Different Tag Types and Functions Used

To make this work I used a few different tag types and built in VTScada functions. Make sure you have the server clock set to 24hr to make this work as written.

Functions:

What's the active rate?

For this task I started at the end and worked backwards. I created a Calculation tag that would record the current month cost, and a totalizer tag to calculate the current energy cost.

The calculation tag is straightforward, it sums the energy cost and base charge.

The totalizer tag multiplies the current power by the active rate

The active rate tag is where all the magic is. The [ActiveRate] determines which rate should be used for calculating energy cost at any moment.

There are three rates,

[Standard]: This is the rate you would be charged with a straight KWHR only charge
[Off-Peak]: This rate is used for holidays, weekends, and between 11pm-7am.
[On-Peak]: This rate is used during the winter only and between 7am-12pm and again from 4pm-11pm.

Calculating the Active Rate

Before creating the expression for the [ActiveRate] I created my triggers. I was originally going to use trigger tags for the various times, but decided on calculation tags and using the built-in time and date functions.

With the tags here I can calculate the [ActiveRate]

What Month is it? [Month Peak]

Using the Date() function I can grab the month number. If its 12 (December) or (that's the || ) January or Febuary, then return 1, else return 0.

You can use TRUE/FALSE, X/Y, etc for this difference, but for this type of calculation, and for how I do [Holiday] I prefer to use a number.

What day is it? [DayofWeek]

I do something similar for getting the day of the week. What I want to know is whether or not its a weekday. If its a weekday I will return a 1.

What time is it? [TimeBlock1] ...

The three time blocks are similar. There are four timeblocks, but the fourth isn't calculated. I chose to leave out the one from 11pm to 7am, it is assumed that if non of the others are true, it must be this time block.

Is it a Holiday?

To determine if its a holiday or not, I created a Holiday tag and then added all the holidays together.

I could have OR'd them together to get the same result, and may change that in the future.

Something that I want to improve is have a static [Holiday] tag by adding an expression that figures out the year and concatenates that on the reference tag. By doing that I can just add 2021Holidays, 2022Holidays, etc. and never look at it again.

The Holidays that count for [Off-Peak] rates are on the NS Power Tariff page:

I create a calculation tag for each and manually add the month day for each -

Another Way to Handle Holidays

There is another way to do this where I change the [2020Holidays] context with just [Holidays] and then OR all of them together, but I decided that was too "messy".

This keeps the tag structure cleaner and sometimes cleanliness of code is more important than simplicity. Always think about what Future You will think about Past You. I know I question Past Me and my decisions when looking at code and designs all the time.

Putting the [ActiveRate] together

Now I have everything I need to put the [ActiveRate] together.

For expressions like this I use Notepad++ or something similar. You can format it nicely so you get all the commas, brackets, etc in the right place. When adding it directly expression box in VTScada it starts to get messy.

This expression is two nested IfElse statements. The first checks to see if its [On-Peak]. On-Peak is only valid when [TriggersMonth Peak] is true AND its in time block 1 or time block 3.

If that expression isn't true, I check to see if its [Off-Peak]. This is any holiday (or the Monday following) OR the weekend OR the missing time block.

Finally, if its not [On-Peak] or [Off-Peak] it must be [Standard].

Looping back to the start

The active rate flows back into the totalizer we started with and we are calculating the energy cost based on the time of the day.

Calculations in VTScada

2020-05-11T13:05:00-03:00

You already know I like VTScada as my HMI/SCADA application of choice, and being able to add functions and calculation to tags is another reason I like it. Its what I use for my Home Energy Management system.

Calculation and Context tags don't count towards your tag limit, so all these tags that I'm adding won't add towards your 50 tag limit.

Calculating cost of energy

The example I'm using is part of the energy management system that I'm putting together at the studio. This is calculating the power using the NS Power Domestic Service Tariff.

The domestic service tariff is:

(Monthly usage in kwh * Base Rate) + Service Charge The Base Rate is currently 15.805 cents/kwh The Service Charge is $10.83 / month

Step 1: Add Constants

First lets add calculation tags for the Base Rate and Service Charge. This way when they change (increase) you only have to change a single tag.

Next type in your name. I have organized my tags such that this is in a Calculations/Tariffs structure. This is using the Context tag type, something that helps with organizing tags.

Then go to the Calc tab. We are using a Constant for this tag.

To make sure that I don't mix up dollars and cents, I'm making everything in $. The reason I chose dollars is to make the Engineering Units look clean in the Display tab

Now do the same for the monthly base charge.

Step 2: Calculate kilowatt-hours

If you have a meter that you are reading KWH directly, and it is resetting for you, you can skip this step. To keep the number of tags to my SCADA as few as possible, I am only reading kW and am using a totalizer tag to calculate my kwh.

First I create a Totalizer Tag to calculate the kw-s.

I have the totalizer looking at the Power tag as the source.

This tag resets every month.

Step 3: Convert kWs to kWh

Then in another calculation tag I do my first expression for this example, and call it kW-HR. In this I select expression and the input box on the right.

This expression is very simple, I divide the [kw-S] tag (which is in the same "folder" as the kW-HR tag I'm creating) by 3600, the number of seconds in an hour.

When you select OK, the value will show up in the Calculation tag box. At this moment we have used 687 kWh this month.

Step 4: Putting it all together

Now for the last step, calculate the current cost of power this month.

For this we create our last calculation tag of the example:

I have placed this tag in the Monthly Power context and had to reference up a couple levels in the tag hierarchy to get to the right one, [Calculations\Tariffs\Standard] and [Calculations\Tariffs\Standard Base Charge].

The result of this equation, as of today, is: $120

Installing VTScada

2020-04-03T17:35:00-03:00

Compared to a lot of industrial software VTScada is very easy to install and get started with.

A few years ago I went through the process for a client to figure out what was the best solution for their company. I choose VTScada and have NEVER regretted that decision.

Where to get the download

The download for VTScada is very small, only 180MB and its a single file. To download you can click here or go to their website.

I like to install the latest version in the default folder, and then keep older versions in custom folders as needed.

The installation process is pretty straightforward, but if you have any issues let me know on twitter or in the comments and I will help you out.

If you don't have a license, use the free VTSCADALight license. It gets you everything you need to get going.

Once its installed

Once you have the latest version installed it will look something like this. Version 12 includes the ability to create lists of the applications.

I have four lists:

These allow me to keep the application screen clean and keep track of what I'm currently working on.

Creating a new application

Creating a new application is straightforward. When you are starting from scratch you click the hamburger in the top left hand corner and then add new application.

The Quick add feature will allow you to get started right away with an brand new, clean application.

If there you need something a bit more complicated, you have Advanced. From there you can create an application from a backup, or changeset. If you want to create a brand new application you can clone it from a changeset, and finally, if you are on the same network you can get from workstation.

I use all of these from time to time, when I land on site and am ready to install on the client's server I almost always use get from workstation. The workstation being my development laptop that I have with me.

Naming Matters

Make sure you name the application something you are going to like. That is what the folder is going to be named by default.

And that's it.

You've installed VTScada and are ready to build your first project at home, or maybe just monitor your hydroelectric station.

Should you be concerned about Arc Blast?

2020-02-06T07:20:00-04:00

Short answer yes, but how concerned? Well that's a harder question to answer.

As far as I'm aware, there hasn't been a single arc blast fatality, regardless of the incident energy. This doesn't mean that it isn't a hazard but the risk associated with that hazard may be lower than you have been told.

Arc Flash and Arc Blast

There is no correlation between the arc flash incident energy at a bus and the arc blast risk. The current equation for arc flash incident energy, published in IEEE 1584-2018 is:

Its has grown in complexity since 2002, and if your interested in how to apply this by hand, Allumiax has an in depth Arc Flash Calculations Using Mathcad post where they compare the results using ETAP.

For arc blast the Crawford-Clark-Doughty model is much simpler and has been verified with testing (within shorter time periods):

What does all this mean?

Starting with what it doesn't mean, it doesn't mean that any PPE over 40cal/cm2 is just a body bag.

As I mention i a reply, I can't disagree more with this. Almost 4 years AFTER a paper was presented at ESW with actual measured results, trainers are still promoting this myth.

From the conclusions from the paper I referenced above:

The theory that copper vaporization is a substantial component of arc blast is not supported by these experiments but it could be a small component.

While there is metal vaporized in the arc, this reaches an equilibrium quite quickly and can no longer contribute to the pressure making its overall contribution quite small an unmeasurable in our experiment** and so inconsequential to be useless in equipment design of a macro scale like electrical equipment

What this tells me, is that arc blast is an issue, but not necessarily correlated with the arc flash incident energy. There can be an arc blast where the door of the switchgear comes off, but relatively low incident energy because the protection trips quickly.

More likely though is the arc fault is in the 5-10kA range for an extended period causing a large incident energy. You can have a 65cal/cm2 arc flash with minimal arc blast as a result.

No body bag needed.

Closing

What do you think? Is an arc blast a significant risk that we need to look at better? Do we, as an industry need more research on the results?

Connect a SEL-849 with VTScada

2020-02-04T05:52:00-04:00

I'm helping a client troubleshoot an HPU motor tripping. There isn't any monitoring of current and they are running out of ideas.

I suggested we pick up a SEL-849 and tie it into the SCADA and trend the current and figure out how that works. This post is a tutorial on how to get started and set up communications.

Everything in this tutorial is for VTScada 11.3 and earlier. I will update with a new post with VTScada 12.x, but it will be very similar.

Step 1: Get everything connected

I bought the 24/48V model. Everything I design is 24V now, the cost difference is insignificant when compared to the ease of troubleshooting without voltage rated gloves.

I have a small bench setup and connected my labelled cable and fused it at 0.5A.

I then connected the ethernet port (Port 2A) to my desk switch and turn the relay on.

Connecting the first time

The quickstart guide has the default IP for the relay, make sure you change it. I followed these steps to get connected the first time:

Find the IP (169.254.0.1)
Change the IP of the computer your using to be on the same subnet as the relay - I used 169.254.0.10
Open a browser and type in the relay IP.
Finally log in with default ACC and 2AC passwords:
1. ACC psw: OTTER
2. 2AC psw: TAIL

You're Connected

The next steps - Securing

Before I do anything else I change the IP and default passwords. I don't want to forget to do this later.

You can change the IP address within the Ethernet Port 2 Settings. For this project the IP range is in the 10.0.1.x subnet.

And then I changed the passwords:

Now for Modbus

Verify that the Modbus settings look like this.

The modbus usermap comes pre-set with most of the functions that you are going to need, but I added one more, IO Status. Its IO_STS here:

Now we're ready to set up the device in VTScada

VTScada Setup for SEL-849

Like most things VTScada, this is pretty simple.

My first step was to create a context tag for "relay" so everything will be easy to add and then remove when we get to site.

Next I add the TCP/IP Port as a child with the following settings:

Then I added the Modbus Compatible Device Driver as a child of the port.

The settings for the driver are:

Finally the IO

I will show the addressing for a single analog and a couple of digitals. From there the pattern stay the same. I added the IO_STS so that I can double check the addressing on the bench.

The first analog in the Modbus table is the current magnitude on phase a, IA_MAG. The address is 40001

Typical for analogs in the usermap, they all start with 40 and end with the line of the usermap.

The first digital on the make is the 25th line, Trip Alarm 1. These are all 16 bit. I named the tags with the SEL shortcode and the bit number, so the first one is TRALRM_1 00 and the description is Overload Trip.

The addressing is in the 30xxx range with a "/" and the bit number. The overload trip alarm is bit 30025/0 by default.

And then you're done. You have communication set up and can add the rest of the points that you need. There are a lot of them.

Troubleshooting, SCADA and Energized Work

2020-01-30T06:29:00-04:00

This is a great followup and use case for a home energy monitoring system, something I wrote about on the blog last week.

My new ETS was broken, but how?

The electric thermal storage (ETS) unit mentioned in that post stopped doing what its supposed to.

When we had it installed I didn't tie it into the PLC because of time commitments, so the contractor put a programmable thermostat in as the charge controller. If its within the right time AND the temperature in the room is lower than the setpoint it start charging. The internal charge thermostats turn off the charging for the three rows of bricks.

This weekend we noticed that the unit didn't stop when it was supposed to. We also had a minor flood in the basement this weekend so I put the thermostat in manual to just get the heat going to dry it out, so we initially thought that was the problem. Turns out, no, it was something bigger.

Before we even had to break out the control schematics, we were able to figure out what was likely going on.

SCADA as a troubleshooting tool

By using the heating screen on the SCADA, the backbone of the Home Energy Monitoring System, we were able to troubleshoot the system without exposing ourselves to 208V. All the covers could stay closed.

To do that we monitored the power output from the unit modifying the various controls that would turn the unit off. When the only action that would shut it down was the breaker we took to google.

Turns out that these units have a failure mode that the charge controlling relay "sticks", and that is where I will get looking today to find out if there is anything that I can do to fix it.

Moral of the story

This isn't about the home energy monitor, basement floods, or even ETS; this is an example of using properly calibrated (and tested) SCADA and troubleshooting procedures to identify the likely culprit to an issue before opening a panel.

CSA Z462 and NFAP 70E have a provision where you don't need an Energized Work Permit for troubleshooting, because troubleshooting isn't "work". While troubleshooting energized isn't "wrong" that doesn't mean that its safe.

When you have input during a control system or SCADA upgrade, include provision for troubleshooting telemetry and using a platform like VTScada the cost per IO (in SCADA hardware and licenses) is minimal when compared to a safety incident.

This same telemetry can be used for advanced asset management which has other business applications.

Don't expose yourself to energized parts, unless there really is no other option.

Get out of the way when operating switches

2020-01-24T08:02:00-04:00

When I am developing an Arc Flash Analysis report there are a few recommendations that always survive. They are near the top of the hierarchy of controls, and are set it and forget it type of controls.

One of these is remote actuators and racking mechanisms.

Both of these systems removes the electrical worker outside the arc flash and shock protection boundaries, removing the hazard (Elimination).

Not a new idea

The first paper I read about the importance of getting distance when operating electrical equipment was 7 years ago, but before that I remember an electrician hitting a push-button with a broom handle.

It was an Electrical Safety Workshop paper titled "Removing yourself from hazards during equipment operation". I read it a few years before going to my first workshop.*

There have been a few advances in remote operation technology since this paper.

What is a remote operator?

A remote actuator is a method to open or close a switch or breaker remotely. For most power circuit breakers this may just mean relocating the Open/close push buttons outside the boundaries.

For handle operated switches this means adding a device to the unit that will mechanically or electrically move the switch into the desired position.

Operating a properly maintained breaker/switch in its normal position isn't a high risk activity. If the state of the equipment is not known or if there isn't a current Arc Flash analysis, it may be prudent to do as much remote operation as possible

What does remote racking look like?

Remote racking on the other hand can be a high risk activity, and depending on the electrode configurations added in IEEE 1584-2018, the arc could be ejected toward the worker.

Remote breaker racking is where the industry is moving as a standard. Both for new construction and by using remote operators on existing equipment.

https://www.youtube.com/watch?v=RQSj7MAy-fQ

I'm not connected with CBS ArcSafe in any manner. I've specified their equipment for clients and haven't had any issues with their equipment.

* If you want to get the best and most current information regarding electrical safety, the Electrical Safety Workshop is a annual conference that needs to be on your list. I try to go every couple years to catch up on all the changes in the industry.

Home Energy Management

2020-01-22T08:36:00-04:00

One of the great things about volunteering with IEEE is that you get opportunities to share some of your expertise with your peers. In December a colleague and I submitted a proposal to fund an Energy Management Workshop.

My System at the Office

A few years ago I set up an energy management system at the office. I tried a couple of the market solutions at the time, but everything was locked up in the "cloud".

I finally decided to go the custom route and found a great company that built energy monitors called GreenEye by Brultech. Around the same time Trihedral released VTScadaLight.

With these tools I can do just about anything.

What did I do?

Back then we used Excel to connect the energy monitor to VTScada, this has some drawbacks, but it has worked well for a few years now.

GreenEye Energy Monitor

The greeneye is overkill for a lot of reasons, 32 CT channels, pulse counters, and temperature monitors.

I have 8 channels set up to monitor the following groups:

Heat
Major Appliances
- Water Heater
- Dishwasher
- Stove
- Dryer
Lights
Everything else

With this information I am able to determine how we use our home, how home upgrades affect our power usage, etc. But to do that analysis we need a recorder.

VTScada

This is where VTScada comes in. With VTScada I'm able to make all kinds of graphs showing the mains voltage, instant power, etc. I can also use the included historian to look at any combination of information that I may like.

The VTScadaLight version that I use for this has a couple of limitations, but nothing that gets in the way for a system like this. The biggest is the 50 tag limit and limit to one web connection.

If either of these get in the way for your installation, I have 200 tag licenses for sale here.

What has this system given me?

With this historical information we have been able to make the following major decisions and changes in the way that we heat the home to save operational budget in business speak.

The first upgrade was installing a heat-pump, the next was installing a electric thermal storage (ETS) so we can get on Time-of-Day (TOD) rates.

Heat-pump

The first major change was to replace our pellet stove with a heat-pump. We always thought that the pellet stove was a cheaper way to heat the house, but when we looked at the cost of pellets and electricity for the stove a heat-pump was way cheaper to heat the home.

Time-of-Day Rates

The bigger decision was switching to time-of-day rates. Even though we use the entire space all day, we would be able to save about 12% a year in electricity charges. The NSPower tariff structure is here - https://www.nspower.ca/about-us/electricity/rates-tariffs/domestic-tod/time-of-day-rates

To get the TOD rates we installed an ETS that heats the studio during the off-peak hours to keep the office warm all day. We did a little additional insulating at the same time. You can see the results in the graphs above. There is a big continuous load from 11pm till early morning.

Normal Habit Changes

We made similar changes to our normal habits, including only washing dishes at night, early morning showers, clothes drying at off-peak, etc.

We will have our first bill in the coming weeks, I will make another post with our Year-over-Year changes.

Where am I going from here?

There are a few things that don't work the way that we were hoping, one is the hot water heater. We need a new one, and I want to "tune" the heater schedule.

After this, the majority of the work needs to be done with the SCADA system. I want to be able to estimate the energy cost using calculation tags in VTScada, that don't count to the 50 tag limit, so we aren't surprised when the bill comes from NSPI.

Time is a fickle thing when it comes to programming.

Updating the connection

A really big change that I am working on is how we pull the data from the GreenEye into the SCADA. I want to get rid of Excel as the middle-man and use something that is more robust and "standard". For that I'm looking at a couple of solutions:

Build a custom driver for VTScada to pull the data directly.
Convert the Greeneye to Modbus on the server

I'm pretty sure I will be focusing on the second option for the workshop and then working on getting the first option figured out for future installations. There are a couple of GitHub projects that I think will be able to make it work, jkeljo/greeneye-monitor and riptideio/pymodbus. One gets the GreenEye data into a python script and then I can convert that to modbus that will connect with VTScada.

Energized Work Permits

2020-01-17T13:45:00-04:00

Let's talk about energized work permits. I've seen some extremely long and detailed forms outlining what needs to be in the energized work permit that were up to 6 pages. To make things worse, they duplicate a lot of the information that would be in the work order (WO) and job specific risk analysis for any task.

The energized work permit (EWP) supplements these documents, but doesn't replace them.

What is an Energized Work Permit

Before you start designing your energized work permit, make sure you have a job safety analysis form, a documented tail gate meeting; and a detailed work order system. That way, the energized work permit will be adding to these documents without adding extra paper to the process. The EWP can reference the WO number and the job safety analysis number. Then add in the specific electrical task risk analysis, list the other checklists that will be used to minimize the risk to the worker, and get signatures from the person issuing the WO, the person asking for the energized work, and finally someone on the safety committee.

This means that the form shouldn't be more than a single page, and when it is used it is part of a larger process that has a proper chain of documentation. Every document in the chain should be as long as necessary but never longer. And the time they are used should be immediately clear. The way that I suggest to people is that there be a checkbox on the WO input form, or the job safety analysis that asks, will this work include the worker doing work while exposed to energized parts? If so, then the EWP is triggered. This would also apply to other checklists/permits. Does the equipment need to be electrically isolated? If so, that will trigger the Lock-Out-Tag-Out procedure.

By doing it this way a very simply workflow can be produced and then treated like an "infographic" and placed everywhere around the workplace. If someone asks if a EWP is needed, you cna walk them through the decision tree once and then they can refer back the next time. The more the decision tree is used and as edge cases discovered, the tree can be updated as per the continous improvement process.

Signatures are critical

Signatures add gravity tot he decisions being made, the requester may think twice about having to approve the work plan and rather than expose the worker to the hazards agree to scheduling a shutdown so the work can be completed de-energized. The requester isn't always an electrical person, so having them review and sign on the dotted line gives them incentive and an opportunity to find non-electrical ways to lower the risk of the work.

This may be by switching piping to the secondary system allowing the main system to be isolated. Before the EWP this option may have been seen as too difficult or costly, making it easier to do the work energized.

I'm not implying that the requester was negligent, but they may have never been trained in that area and would be completely unaware of the hazards of doing energized work. It would be a similar case if an electrican requested a mechanic to do work under a piece of equipment held by hydraluics but refusing to let them place blocking.

A good starting point

There are a lot of great EWP drafts online, and we are putting one together for you too, but before you just grab the longest one that seems to have all the fields you need, re-read this email. Make sure that you aren't making the process harder than it needs to be. Make the process of using an EWP simple and this will encourage everyone to go through the risk analysis process and document everything they do.

Without documentaiton you can't improve the process, you can't make your work place safer in a predicable and repeatable fashion.

My ask

I really would like to know what you think about this electrical safety newsletter. Are you getting value, or is it something that you just leave? Do you prefer longer ones like this, or short and sweet?

Finally, don't use an energized work permit as a reason to do energized work. Don't do energized work when you can avoid it.

Electrical Safety Programs

2020-01-09T17:27:00-04:00

Start Writing about what this is all about. This is the thing that we are talking about, some of the steps to get you started in developing an electrical safety program for your workplace. This will get you started.

Getting Started

Before you get started, its important to figure out what are some of the typical tasks that electrical workers do at your workplace, some questions that get you started could be:

What are the electrical hazards in your workplace?
What jobs require work on energized equipment?
Who performs the work on energized equipment?
How do you currently reduce risk of harm to personnel and equipment?
If you already have a safety program, is it adequate? How long has it been since it has been reviewed?
How long has it been since the last incident energy study has been done on your workplace? Should your studies be updated?
Who needs to be trained to work at your facility and what kind of training do they need?
What kind of PPE is required for which types of jobs?

Getting Resources Together

Now that you have compiled a list of tasks, people, roles, hazards, etc; you need to get some resources together.

In the past I suggested that you put together a table of contents listing out all of the sections that you will need. Today, I think that is too onerous for a starting point, and if you are doing this in addition to your regular job, I think that it will just lead to the electrical safety program never really getting started. Instead, I recommend making a list of all teh resources that you have today. Maybe its the Electrical Safety Starter you got from me when you joined the weekly electrical safety newsletter; or the handbook that came with that Arc Flash Course. Anything and everything you have.

Next you need to put together an improvement schedule. Keep the cycle short starting out, and as the program matures, you can stretch it out. I recommend NEVER having a cycle more than a couple years though. This is the first part of the Plan-Do-Check-Act cycle. We are planning the next steps. When you have this written down, talk to your managers, safety officers, electrical workers, etc. You need to make sure you have everyone's buy-in.

Roles and Responsibilities

You have the schedule and you have the buy in, now you need to define who does what, and who CAN do what. Start small. The minimum roles would be: Safety program owner, electrical worker, non-electrical worker.

You need to define what these roles are within the electrical safety program development and how someone qualifies for each role. The non-electrical worker would be defined as someone that works in and around electrical equipment; never entering the restricted area, but aren't qualified to do electrical work. This could be a mechanic that does work on motors and they will be activating isolating switches as part of their work and using bump tests to verify that the motor is de-energized.

Electrical Safety Program Requirements in Canada

2019-05-09T19:43:00-03:00

Something that I have been thinking about lately is: What are the electrical safety program requirements in Canada.

OSHA covers all of the USA, and the minimum Electrical Safety Program requirements can be found here - 1910 Subpart S.

In Canada, the Canada Occupational Health and Safety Regulations, part VIII mentions written procedures a couple of times, but not very clear if this needs to be an electrical safety program, or just a couple of written checklists.

"the employer shall issue written instructions with respect to the procedures to be followed for the safe performance of that work"

from Canada Occupational Health and Safety Regulations

How about the provinces?

The rest of this article will have the various provincial regulations to find out what they say, and how clear they are regarding the requirement of an electrical safety program.

Newfoundland and Labrador

The Occupational Health and Safety Regulations in NL are pretty clear in the assumption that the employer has an electrical safety program in place. They mention it by name in two different places:

Low voltage electrical equipment - 482(2)
- "Where it is not practicable to completely disconnect low voltage electrical equipment, work shall be performed in accordance with an electrical safety program in accordance with a standard acceptable to the minister that... "
Isolation and Lockout - 490(2)
- "Where it is not practicable to completely isolate high voltage electrical equipment an employer shall conduct a formal hazard assessment and develop an electrical safety program that..."

Newfoundland and Labrador appears to be very clear that they expect employers that interact with electrical equipment to have an electrical safety program. They mention it by name in two places, both having to do with the isolation of electrical equipment.

In section 484(2)(e) they even mention that current diagrams are required. These diagrams, in my opinion, don't just include the single line, but all control and protection infromation for the equipment. Many times the wiring and schematic diagrams for control panels are not updated after changes.

Nova Scotia

The Nova Scotia Occupational Safety General Regulations Part 11 covers electrical safety, but they don't mention an electrical safety program specically. In fact, the NS regulations are written in a fashion that makes it seem that working on energized equipment below 750V is NOT hazardous work. You read that correctly. Here is the quote from subsection 125(2)

125 (2) An employer shall ensure that no work is performed on an energized electrical installation rated at greater than 750 v phase to phase unless the competent person performing the work is accompanied by another competent person.

From NS Occupational Safety General Regulations on May 9, 2019

This is crazy! CSA Z462-2018 uses 30V as the threshold for whether the shock hazard exists, and if a shock hazard exists mitigation techniques need to be implemented to lower the risk. The shock protection boundaries start in at 30V in tables 1A and 1B. The only limiting distances mentioned in the NS regulations are for overhead lines, and they start at 750V.

Prior to the 2018 version of CSA Z462, the threshold voltage was 50V, it was lowered to 30V; the 750V threshold that is implied to be a part of "Hazardous Work" is way too high. Wow.

I'm not done yet.

I have the two provinces that I do the majority of my work in covered. More to come as time allows.

Checklists

2019-02-15T14:02:00-04:00

Today I'm starting a new-ish feature where I'm publishing a different thought as a twitter audio at least, and maybe a video depending on where I'm located.

This first thought is on checklists, and their importance in every electrical safety program. This came to me, again, when I was meeting with a client and they were getting started developing their electrical safety program. I was there to help them with an arc flash analysis update, and we started talking about the minimum viable electrical safety program.

Some background

To get there, I had to fly and I noticed something that I see every time I fly, but I haven't thought about in a while, the pilots were doing their checklist. This was a short flight, and these pilots must do the same routine pretty much every day. They know it in and out, but the checklist helps them consiously go through all the steps every time. Its like if you drive the same part of raod often and then one day completely forget drviing it as you go though. You don't want to space out on routine tasks.

This is where the checklist comes in, with a very routine task you may skip over steps, but with a checklist you make the check as you go through, mentally remembering to do that thing. I recommend that checklists be used for all tasks that are high risk starting out, and then add in non-routine medium risk tasks as the electrical safety program matures. An example of a medium risk task may be changing a 347V ballast at height.

Minimum Viable Checklists

The two checklists that ever electrical safety program should have are:

Energized Electrical Work Permit
Lock-Out-Tag-Out

These checklists allow the worker and manager to manage the hazards associated by those tasks, which are always medium-high risk, to make sure that everyone stays safe.

Battery Economics and Grid Stabilization

2018-06-19T16:46:00-03:00

I read an article last week about how using electric cars for grid stabilization will shorten the life of the batteries. In fact the article uses the trigger word detrimental!

But if you understand how the electrical utility industry works, and some basic understanding of battery chemistry, that's a no brainer. The real question is how detrimental is it? How much shorter is the total life of the battery? Is that increase in depreciation more than the utility will pay for another energy source on a second by second basis?

This is not a hindrance to the technical implementation of electric cars, household batteries like the Tesla Powerwall and other distributed sources as a grid stabilization means. Its an economics and business challenge.

Can you provide enough revenue to the car owner (asset owner) to cover the increased depreciation of the asset and a reasonable profit? Is this expense from the grid operator more or less than it would pay to a different party in the market for a similar service?

See its not that the idea to use car batteries is bad, its that in today's market there is no feasible way to provide the generation services the utility needs in a way that they can use. To give an everyday analogy, you don't buy gas for your car by the milliliter from your neighbor, you go to a service station and buy it by the liter. utilities do the same thing; however electricity isn't gasoline, its tied to a network and if you can aggregate a lot of different sources in a local geographic area; and offer it to a utility in a way they can integrate to their system, now it can start to make sense.

However, today that isn't possible, but not for technical reasons for practical ones. There aren't enough cars (or other assets) connected to the grid and the cost of generation isn't high enough to cover the added depreciation to the asset. This is changing and we are spending a lot of time researching ways to make this happen, sooner. It won't be long before you will be asked to sign up to be part of an aggregated pool to sell energy to the utility and then get a small cheque based on how much the aggregator sold both locally and internationally.

Over the next couple of months I will be deep diving in on this topic and others in our newsletter. It is at most once a week and at least once a month, all depending on what we have to say at the time. You can join below!

VTScada Certified Solution Provider

2017-04-24T15:14:00-03:00

Software for Monitoring and Control

Effective immediately JMK Engineering is a VTScada Certified Solution Provider.

We are proud to be a partner with Trihedral, creators of the VTScada SCADA System.

Coming Soon

Jeff has been tweaking a home energy monitoring system using VTScadaLight and a GreenEye monitor for the last couple of months. We are planning to set something up in the next few months showing you how to do it at home. This is something that has all the power of a cloud based solution, but is yours to control.

To learn more fill out the form to sign up for our newsletter below.

Generator Protection: Grounding and Ground Fault Protection

2016-11-03T11:00:00-03:00

An important part of generator protection is that generators need to be grounded. And because they need to be grounded, generators are susceptible to ground faults. This article is going to talk about general case ground faults on a generator and the appropriate use of generator protection, and then talk about the specific case of a ground fault on the generator field coils.

Ground Fault Generator Protection

One of the most important things to note when protecting against ground faults is that the higher the magnitude of the grounding impedance, the smaller the magnitude of your fault current will be. This makes it difficult to detect weaker faults with high resistance grounding. For example, a differential relay might not pick up a single phase to ground fault because the current magnitude change is not enough to cause the relay to trip.

With high resistance grounding, you need a relay on the grounded neutral to catch ground faults that are single phase to ground, since the relay on the neutral doesn't care about load current. However, when the magnitude of your ground resistance is high enough, it becomes difficult to differentiate between low magnitude fault currents and harmonics.

An important thing to remember is that all of the relays in your generator protection system need to be coordinated in order to function properly. The last thing you want is for a ground fault detected on a relatively unimportant piece of equipment, like a table saw plugged into the wall, to kill the power to your whole building!

The following image is an example of a unit-type grounding system.

This is a fairly common grounding configuration for generators. There is a high resistance ground at the generator, connected to the system through a distribution transformer. The resistor and the relay are grounded in parallel on the grounding transformer.

Now that we've talked about generator protection for ground faults in a general case, I'm going to talk specifically about generator protection in the case of field grounds.

Field Ground Generator Protection

A field ground is exactly what it sounds like: a ground on the field of your generator. A single phase to ground fault on the field of a synchronous machine should in most cases produce no immediate damaging effect. Don't let this fool you though: the field ground fault still needs to be cut off. A single phase to ground fault on a field is dangerous because a second ground fault could short part of the field winding, causing damaging vibrations. A field ground fault must be detected and removed quickly and efficiently.

The following is a circuit that could be used for field ground generator protection.

In this circuit, the relay uses a voltage divider consisting of two linear resistors and one non-linear resistor. The resistance value of the non-linear resistor varies with applied voltage. When the field becomes grounded, voltage develops at the point between thetwo resistors and the ground. The magnitude of this voltage depends on the exciter voltage of the generator, and the location of the ground. The maximum voltage value is obtained if the field is grounded at either end of the winding.

There will be a point on the field winding where a ground fault will produce no voltage between the middle point and ground. This “null point” is the point on the field winding where there is an electrical balance between the two field winding resistances and the two relay resistances. The non-linear resistor varies the location of this null point so that a ground can be detected at any point in the field winding.

Finally, you have a pushbutton connected across a portion of the R2 resistor. This permits a manual check for possible ground faults at the center of the winding. This is so that if the generator is base loaded and will not experience periodic excitation variations, you can still check for ground faults.

Closing

Hopefully now you have a better understanding of how to use grounding and relays to provide generator protection against ground faults. If you have any more questions, feel free to shoot me an e-mail at jeffmackinnon@jmkengineering.com.

As always, thanks for reading!

How to Detect Generator Faults with Generator Protection

2016-10-27T11:00:00-03:00

Your generator protection must have a way to detect generator faults. A fault is any unwanted current flow in an electrical system. Faults can cause all kinds of problems for your generators, including current loss, interruption of power delivery, and damage to the generator due to overheating.

There are three things your generator protection needs to do when your system encounters a fault. First, the protection system has to detect generator faults. Next, the circuit in which the fault occurs has to be tripped. Finally, the specific physical location of the fault has to be found so that the fault can be repaired.

How to Detect Generator Faults: Multiphase Faults and Differential Protection

One of the best ways to pick up multiphase faults on any machine, generators included, is by using differential protection. This is a fairly simple implementation of protective relaying.

The circuit consists of:

Two current transformers (CTs), one on either side of the protected equipment. We'll call these A and B.
A relay between the two CTs.

Here's how this circuit can detect generator faults: the logic is that the current going into the generator should be the same as the current coming from the generator. The relay is tripped if the difference between the current passing through A and B grows too large.

You want to make sure that you use a percentage differential relay here to mitigate error that could be caused by non-identical CT properties. In an ideal world you would have ideal CTs, and they would have the exact same properties. Real world manufacturing processes try to get as close to this as possible, but your CTs will always have some kind of tiny differences. So instead of the relay tripping when the difference is a hard value, it trips when the difference is a percentage away on either side of where the current value should be.

The problem now is that you know the general area of where the fault is, but do not have an exact location.

Locating the Fault

So you know how to detect generator faults, and based on where the relay tripped, you have a rough idea of the location of the fault. What you need to know now is the exact location of the fault so that the fault can be repaired.

As usual, before starting work, make sure that the section of the system you are going to be working on is de-energize. It's time to troubleshoot!

The first thing that you can do is look for any visible signs of damage. Any kind of blackness as though something burned is a good indicator of a fault location (or at the very least something that needs repairs). If the fault occurred very recently you'll probably be able to smell it too.

The next thing you can do is test the circuit with your trusty multimeter. Start at one end and work your way through the circuit. If you can, get your hands on the circuit diagram and find out what the multimeter is supposed to read if the circuit is operating properly.

If you can't get at the circuit for one reason or another, you can try a time-domain reflectometer. These send a pulse down the wire and pick up changes in impedance, which reflects the signal back to the device. This will tell you how far down the line your fault is.

Closing

So that wraps it up! Hopefully now you know a little bit more about how to detect generator faults and how to locate a fault once it's been detected.

As always, thanks for reading!

Generator Protection: 7 Things that Wreck Your Generator

2016-10-20T11:00:00-03:00

Generator protection is an important part of having a reliable power delivery service. Electrical systems are complex, and the failure of a generator can mean loss of critical plant systems. If you don't have generator protection and your generator fails, you lose tens of thousands to hundreds of thousands of dollars in repair and replacement costs (depending on the size of the generator).

Not only that, but losing critical systems due to a lack of generator protection could result in extreme danger to anyone working in the facility, or even just anyone relying on the electricity of the generator for anything! Think about the costs of a generator failing in a remote northern location: if the heat is electric, everyone is now in danger of freezing to death. If power lines go down in a storm, roads suddenly become much more dangerous as street lights go out. Reliable power is important, and generator protection is one very important piece of the overall system puzzle.

So without further ado, here are 7 different things that can wreck your generators if you do not have appropriate generator protection.

Faults

A fault is any unwanted electrical current flow. Faults can cause all kinds of problems for your generator. For example, if the fault is a short circuit across the generator windings, then the winding could heat up and become damaged. Faults are a common cause of the rest of the dangers you need to account for with your generator protection.

Overload

If the generator cannot supply enough power to its loads, it will not necessarily shutdown automatically. What it will do is overheat, and maybe fall out of synchronization: both of these conditions can threaten to destroy your generator.

Overheating (Windings or Bearings)

Overheating can be caused by a number of things, such as the generator being overloaded, a winding insulation breakdown due to a fault, or insufficient bearing oil lubrication. Overheating a generator decreases its operational life, and can outright destroy the generator if the problem isn't solved quickly enough.

Overspeed

Typically, a generator will be forced to run above normal operating speeds when there is a loss of load on the generator circuit. The loss of load increases the generator voltage which in turn over excites the field and increases generator speed. Much like overloading, this can potentially cause the generator to OVERHEAT.

Loss of Excitation

Loss of excitation can cause your generator to go offline, which will in turn interrupt your power supply. When loss of excitation occurs, generator terminal voltage drops, causing reactive power from the system to flow into the generator. This threatens system stability.

Motoring

Motoring is what happens when the prime mover is not supplying enough power to the generator. The system is forced to make up for these losses by supplying real power to the prime mover, which causes the generator to act like a motor. Real power flows into the generator instead of out of it, and reactive power flows both into and out of the generator.

Unbalanced Current Operation

The biggest problem with unbalanced current operation is that it causes current to flow through the neutral, increasing the power loss in your lines. This can be caused by unbalanced loads, or a fault, and once again, can result in overheating.

Closing

As you can see, while there are a few major things that can go wrong with a generator, the main cause of destruction is overheating.

Now that you know WHAT you need to protect your generator from, the real question is this: HOW do you implement generator protection?

I'll be writing more articles in the future to answer that, so make sure to check back frequently!

As always, thanks for reading. Don't forget to sign up for our weekly newsletter below, where we'll offer all kinds of neat tips and tricks that you won't find on our website!

How Induction Machines Work

2016-10-13T11:00:00-03:00

There are two main types of induction machines used to transmit electrical energy and perform work: transformers, and AC induction motors. In order to understand how they work, first you need to understand the principle of induction.

Induction

Induction is the process by which a magnetic field can induce current in a wire. The easiest way to test this is to slide a bar magnet through a coil of copper wire and measure the current through the wire. As the magnet passes through the wire, an electric current is generated.

Induction Machines: Transformers

Transformers use the property of induction to change voltage and current values in an electric circuit without altering the source of the electricity. At the lowest level, a transformer is made of a metal core (usually iron) with two copper windings (wire tightly wrapped around the transformer core). These windings are referred to as primary windings (where the current enters the transformer from the source) and the secondary windings (where the current leaves the transformer to go farther down the power line). As current travels through the wires of the primary winding, it generates a magnetic field that moves through the transformer core. The core is shaped like a hoop: when the magnetic field reaches the part of the core that the secondary winding is wrapped around, the magnetic field induces an electric current in the secondary winding. The magnitude of this current is proportional to the number of turns of wiring in the winding.

Induction Machines: Motors

The most common type of induction machine is a three-phase, squirrel cage induction motor. An induction motor consists of two parts: a stator and a rotor.

Stator

The stator of an induction motor is the non-moving part of the motor. It consists of three pairs of "poles" for the three phases of AC current. The poles are arranged so that when the phases of the oscillating current flow through them, they generate a rotating magnetic field.

Rotor

The rotor of the induction motor is shaped like a squirrel cage, with a number of metal bars joined electrically at either end by two metal rings (which short circuits the rotor).

How It Works

The rotating magnetic field generated by the stator is moving relative to the rotor. The rotor wants to have the same rotating magnetic field as the stator, so a current is induced in the rotor and it is forced to move to try and line up the magnetic field of the rotor with the magnetic field of the stator. If the rotor's field lined up it would reach "synchronous speed" and stop moving (because the two fields would be in equilibrium). For this reason, the rotor will always move slower than the synchronous speed. The difference between the actual speed of a motor and the synchronous speed of the AC current is called slip.

Torque and Speed

In order for an induction motor to be useful, it has to drive a load at a certain speed. In order to move the load, the motor must generate a certain amount of torque. The torque generated by the motor is proportional to the amount of current that the motor is drawing from its source: more current means more torque. However, the speed of the motor is proportional to the voltage, and voltages at the source are normally fixed. What this means is that if your motor load requires high torque, the high current draw will force the voltage down and this will result in a slow motor.

This is how motor starting works, and most motors are designed to draw a lot of current when they start, in order to generate the torque necessary to move what is initially a static load. As the load starts moving, the torque required to move it is reduced and the motor can speed up. It continues on like this until the motor reaches its operational speed. In the case where for some reason voltage drops, the strain on the motor (from slower speed, higher torque, and higher current) can cause the motor to burn out. You can find out more about how voltage drop affects induction machines here.

When you break them down, induction machines aren't nearly as complicated as they seem! As always, thanks for reading!

How to Read Arc Flash Labels and Determine PPE Requirements

2016-10-06T11:00:00-03:00

In order to protect yourself and workers in your facility, it is important that everyone is aware of how to read arc flash labels. Being able to read arc flash labels is crucial for management in determining PPE requirements, and is crucial for both electrical and non-electrical workers to determine whether or not they currently have appropriate PPE for the task at hand.

Arc Flash Labels

First, let's take a look at a typical Arc Flash Warning Label.

Example arc flash safety label.

There are two important pieces of information about arc flash here that determine the PPE requirement. The first is the Flash Hazard Boundary. This is the minimum working distance where appropriate PPE for energized work will effectively protect personnel against arc flash hazards. Working any closer than the minimum distance specified in the Flash Hazard Boundary can result in serious harm in the case of an arc flash incident because the PPE recommended by the label will not protect a worker from the effects of arc flash.

Next, you've got the energy level of cal/cm square, with a flash hazard at 18 inches. In this case the energy level is 3 cal/cm square. This is the most important piece of information on the warning label: it tells you how severe a potential arc flash incident could be. This number is determined by an incident energy study.

PPE Selection Using Incident Energy Levels

With these two pieces of information, you can now select your PPE. PPE categories are not rigorously defined by any standards organization: the level of PPE required for a particular job is defined by the facility management. CSA Z462 recommends three different levels of PPE depending on the the incident energy level:

Incident energy levels less than 1.2 cal/cm square
Incident energy levels between 1.2 and 12 cal/cm square
Incident energy levels greater than 12 cal/cm square

Level 1 PPE could be anything that covers exposed skin, hearing protection, insulated gloves and shoes, and eye protection. Level 2 PPE would be similar, except that all of the clothing has to be arc rated. Level 3 generally requires arc flash suits and other bulky PPE.

However, there are no hard and fast rules for determining PPE, just helpful guidelines. PPE categories for your facility should be heavily influenced by your Electrical Safety Program.

PPE is ALWAYS the Last Line of Defence!

Remember than PPE is supposed to be the last line of defence against arc flash and shock hazards. Your electrical safety program should consider the Hierarchy of Hazard Mitigation Controls. They are:

This hierarchy of mitigation controls should always be followed to effectively reduce the risk of an arc flash hazard occuring.

The Ability to Absorb Risk is Important

PPE levels are also determined by the amount of risk that your company is willing to absorb. Statistics gathered by the NFPA show that the average electrical accident costs $80,023. This cost includes both workers' compensation (medical bills and wages while unable to work) as well as equipment costs.

If it is more expensive to purchase and maintain PPE than it is to allow for electrical accidents, then you need to look in to the other controls that can be used to mitigate arc flash hazards. Your electrical safety program should outline the process to follow if you cannot provide higher levels of PPE (but can use other controls to lower incident energy levels on the work site). Overall, your electrical safety program and your ability to absorb risk will determine how the PPE levels are developed for your company.

First and Foremost, Your Goal Should Always be to Keep Your Workers Safe!

How Voltage Drop Affects the Operation of Induction Machines

2016-09-29T11:00:00-03:00

Induction machines do not like voltage drop. When talking about induction machines, what most people think about is the 3 phase AC induction motor. For the most part, the power output of an induction machine is directly proportional to voltage and current. If the voltage of a motor drops, the motor must draw more current to compensate. As long as the current being drawn by the motor is within the nameplate limits, this isn't necessarily something to worry about for short periods of time. However, over longer periods of time or with a significant voltage drop, there will be a negative impact on the performance of your induction machine.

Induction Machines Overheating

If a motor is drawing more current than it is rated for on the nameplate, the wires that make up the windings will start to overheat. Overheating for any extended period of time will lead to a loss of lifespan of the motor. If the amount of current it is drawing is too far outside the nameplate rating, the motor will burn out all together.

Battery Life Reduction caused by Induction Machines

If your motor is supplied power by a battery or battery bank, the drop in voltage and increase in current will drain the batteries faster. This is a critical factor when looking at motors supplied by predominantly solar or wind power, which store energy in batteries when there is a surplus of sun or wind and have loads that draw energy from batteries when there is insufficient sun or wind.

Loss of Speed and Torque in Induction Machines

Another thing that happens as voltage drops and current increases is a loss of speed and torque at the motor. This loss of speed and torque can negatively impact whatever process the motor is supplying.

If the speed and torque of the motor decreases enough, the motor will go back to its "starting" state. When starting, a motor requires large amounts of torque in order to start moving whatever load is attached to the motor. In order to get this starting torque, you require a large amount of current. So the current value spikes, which causes the voltage to drop even more! All of this results in a motor that doesn't move and could quickly burn out.

Be Sure to Have Proper Protection!

In order to protect your motors from burning out due to voltage drop, it is important that you size your motor protection relays appropriately so that they will trip when voltage drops and current spikes.

As always, thanks for reading!

What is Arc Flash

2016-08-10T10:00:00-03:00

There are really only two types of electrical hazards: shock and arc flash. CSA Z462 gives a short definition for arc flash:

Arc flash hazard - a dangerous condition associated with the possible release of energy caused by an electrical arc. Arc flash takes two forms:
- Arc blast refers to the pressure wave created during an arc flash incident. This pressure wave can throw molten metal at you at very high speeds in addition to causing physical harm like concussions.
- Arc burn refers to the incredibly high temperature in the area around an arc flash. This temperature can be hotter than the surface of the sun and can cause debilitating burn injuries if you aren’t wearing appropriate PPE.

CSA Z462 mentions that under normal operating conditions, most equipment is not likely to cause an arc flash hazard. It then points to Table 4A for examples of activities with potential for causing an arc flash hazard. Because of the severity of arc flash incidents, it is very important that you understand what it is and how it can harm you.

Arc Flash Causes

An electrical arc occurs when current passes through the air from one conductor to another. A lightning strike could be considered an arc from the clouds to the ground. An arc fault occurs when you have unwanted arcing in your electrical system. This could be because of a breakdown in wire resistance, for example, due to heat. Arc faults can also occur during switching: current cannot immediately drop to zero, so some of the current arcs across the gap as a switch is opened. Undesired arc faults can damage your electrical system.

Arc flash is a severe case of arc fault. In high voltage systems, when an arc occurs it usually burns out and destroys the physical conductors, so air is the only conductor left. Air is normally an excellent insulator, but will break down to plasma when the ratio of voltage to arc length is relatively large.

Arc Flash Effects

A high voltage arc in a small space will have a very large electric field and will cause the air to break down in to plasma. This plasma will use up all of the energy available to it before it dissipates. The plasma will create temperatures as hot as 35,000 degrees Fahrenheit (Clark, n.d.) which is hotter than the surface of the sun!

When an arc flash occurs, temperatures can climb so high that it can burn the skin right off of you! Not only that, but these temperatures tend to vaporize any nearby metals (such as the ones used to make the conductors themselves). When copper (a common wire material) is vaporized, it suddenly expands to 67, 000 times its original volume. (Ray A. Jones, 2000)

Here's a quick example using one foot of AWG 10 wire. AWG 10 wire has a conductor diameter of 0.1019 inches. (Wire Gauge and Current Limits Including Skin Depth and Strength, n.d.) A one foot long piece of AWG 10 wire has a volume of 1.80271*10^-5 cubic feet ((0.1019²/4) * 12 inches * 1 cubic foot / 1728 cubic inches). That seems pretty small. But when it gets vaporized during an arc flash, it suddenly takes up a space of 1.21 cubic feet! Now consider that a cable can be made up of multiple wires: A typical arc flash packs the same explosive power as dynamite (caused by the superheated metal as it expands into vapor). This explosive action is known as arc blast. If the force of the arc blast doesn't kill you, you are at serious risk for broken bones and organ damage, especially if the explosion knocks you into a hard surface. It's even more dangerous if you're working at a high elevation: the arc blast could knock you off a solid foothold and put you at serious risk for fall injury.

Not only does the arc blast cause a pressure wave that can throw you around with a large amount of force, but it will also throw around any metal that didn't get vaporized during the arc flash. Usually so hot that it becomes molten metal, this can burn through clothing as well as any equipment nearby and can cause serious harm to anything it touches. The explosion and high temperatures could also cause damage to or destroy nearby electrical equipment that is not part of the initial arc flash incident.

Overall, arc flash is a great risk to both people and equipment, and can result in very costly injuries to people or damage to equipment. In order to account for arc flash in an electrical safety program, an arc flash study is required.

As always, thanks for reading!

Power Factor Correction

2016-08-05T10:00:00-03:00

One of the great things to do after you get a power system study completed, is implement power factor correction. With power factor correction you will be able to properly support the voltage at your site, but more importantly you will likely be able to save some money. Large loads on a utility are charged on power factor, maximum demand and energy use. At home you will only be charged on energy (kWhr).

If you can increase the power factor to unity, you will save on energy, and any reactive power charges. The maximum demand will be slightly helped, but you will more likely need to change procedures to affect this aspect of the bill.

What is Power Factor Correction?

Power factor correction is any action on an electrical system that brings the power factor of that system closer to unity.

How does it work?

Power consists of both real and reactive components. The real component of power is the part that does all of the actual work. The reactive component of power is the power generated by the magnetizing current in a motor on transformer. This magnetizing current is necessary to operate machines with alternating current, but does no usable work. Power factor correction works by reducing the reactive power component while maintaining the real power component. This reduces the overall current consumption of your system. The simplest and most common way to improve your power factor is static power factor correction (adding capacitors to your system).

Capacitors

In many electrical systems the current and voltage waveforms are out of sync by a certain amount. In an induction motor, the current lags the voltage. A capacitor however is a purely reactive load, and as a result current drawn by a capacitor leads voltage. The effect this has is that as the alternating current cycles back and forth, it looks like the reactive component of the capacitor current and the reactive component of the motor current "cancel" each other out. You can see this is the phasor diagram below.

Fig. 1 is the phasor diagram of the induction motor. The current lags the voltage. Fig. 2 is the phasor diagram of the capacitor: the current leads the voltage. Fig. 3 is the result of adding a capacitor to your motor circuit: the capacitor current and motor current add together to reduce the phase angle and bring it closer in line with the voltage angle.| Three phasor diagrams of voltage (V) and current (I). Fig. 1 is the phasor diagram of the induction motor: the current lags the voltage. Fig. 2 is the phasor diagram of the capacitor: the current leads the voltage. Fig. 3 is the result of adding a capacitor to your motor circuit: the capacitor current and motor current add together to reduce the phase angle and bring it closer in line with the voltage angle.

The great thing about capacitors is that they are cheap, reliable, and come in many different sizes. If you can't find a capacitor with the specific size you need, you can combine multiple capacitors in a capacitor bank.

Where to place the Power Factor Correction Equipment?

Since you want your capacitors to draw reactive current away from your motor load, you want to place the capacitors in parallel with your motor. "You can place the capacitors at the equipment, distribution board, or the origin of the installation. Static power factor correction must not be applied at the output of a variable speed drive, solid state soft starter or inverter as the capacitors can cause serious damage to the electronic components. " (John Ware, IEEE Wiring Matters, Spring 2006).

So there you have it! If you want to perform power factor correction on your system to save yourself some money and possibly increase the capacity of your systems, you have to add capacitors in parallel with your loads. Thanks for reading!

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Arc Flash Mitigation techniques - PPE

2016-08-03T10:00:00-03:00

PPE is the last line of defense when it comes to arc flash mitigation, according to the hierarchy of hazard mitigation. Appropriate PPE selection is important to prevent introducing new risks to workers on job sites.

Safe PPE Selection

In order to select PPE, you first need to have an incident energy study on your workplace. PPE levels are determined based on the incident energy levels of the equipment being worked on, so you can not appropriately select PPE without an incident energy study. CSA-Z462 has a table that matches types of PPE to arc flash incident energy levels. This table is an excellent guide to use when selecting your PPE.

I personally do not recommend doing work on anything with an incident energy level higher than 40 cal per square centimeter: when incident energy is that high, you should figure out a way to reduce the incident energy level before assigning any work. All PPE should be appropriately labelled so that you know what is acceptable to wear for the present work conditions. At minimum, when working on a system with an arc flash risk, you should be wearing arc rated long sleeve shirts, pants, and undergarments, insulated leather or rubber gloves and boots, eye, face, and ear protection, and a hard hat.

Other Factors that Influence PPE Selection

Other factors to consider when selecting PPE include the working environment and the amount of time it will take to complete the job. Higher levels of incident energy require more bulky PPE. Bulky arc flash suits can impede a worker's vision, hearing, and mobility. The large, sealed, bulky clothing is cumbersome and also gets hot quickly, which causes increased levels of fatigue. All of these things can lead to new risks that might actually increase the danger to workers on site, which is the opposite of what arc flash mitigation techniques are supposed to do!

One last thing to be sure of is that your PPE is in good repair. Old, worn out PPE full of holes won't protect you in the event of an arc flash incident, and should not be worn by anyone.

Job Planning

Sometimes it is necessary to do work in heavy, uncomfortable PPE.

When this is the case, it is important that jobs be planned appropriately to reduce risk involved. If fatigue is an issue, schedule multiple people working on the same job in short shifts as opposed to having one person doing all of the work. The buddy system (having at least two people working on the same job) also has the added benefit of safety: the second person can immediately respond if something goes wrong while the first person is working.

You can also assess the functions of the equipment being worked on to see if you can't reschedule work for a period when the equipment can be de-energized, avoiding the need for the bigger arc flash suits.

Worker training is very important. The NFPA notes that many workers who suffer electrical injury have insufficient training and do not properly use their PPE. Training personnel to appropriately assess hazards and risks is very important because these hazards and risks influence the level of PPE required for a job. All workers should be properly trained in the use of all PPE required for a job: if you aren't using the PPE properly, then it won't protect you. Once again, this goes against our goal of arc flash mitigation!

Closing

When selecting PPE, you need to know the incident energy on the equipment you are working on. You then need to make sure the labels on your PPE are appropriate for the work and that your PPE is in good repair. When doing energized work, first try to reduce the incident energy levels to avoid having to wear the bulkier PPE. If that isn't possible, have multiple people working in short shifts to avoid fatigue, or reschedule to a time when you can de-energize the system. Make sure that all employees are trained in the selection and use of PPE.

Stay safe, and as always, thanks for reading!

Industrial Power System Configuration - Main Tie Main

2016-08-01T07:51:00-03:00

Industrial power systems can become very complex, and the related processes need a reliable source of electricity to keep the process running, both for economic and safety reasons. There are many different kinds of distribution systems. This article will only focus on one of them: the Main-Tie-Main system configuration.

Industrial Power System Main-Tie-Main Configuration

Main-Tie-Main, also formally referred to as a "secondary selective system" consists of two independent circuits connected together at the load buses by a tie breaker. See the figure below for details.

Reliability

The biggest advantage that a for an industrial power system that a main-tie-main configuration has over other system configurations is reliability. Usually, the tie breaker is normally open and the system acts as two independent circuits supplied by two independent sources. For example, we will assume that there is a fault on Source 2. This fault trips CB2, cutting off all power to Load 2. Immediately after power is removed from Load 2, the Tie Breaker closes. Source 1 is now providing power to both Load 1 and Load 2, and the system is able to perform its normal functions until the fault at Source 2 is repaired. When normal power is restored and CB2 is closed, the Tie breaker opens and the system resumes normal operation. Operation is only interrupted for a very brief moment, if it is interrupted at all!

The Main-Tie-Main configuration is also good for maintenance for this very same reason: you can open CB2 and perform repairs upstream from Load 2 de-energized, while still supplying Load 2 with power.

Transformer Sizing

One characteristic of the industrial power system main-tie-main configuration is that both transformers must be sized to appropriately handle the load of both buses. In our example, we will assume that both Load 1 and Load 2 are the same size. Transformer 1 and Transformer 2 must each be sized so that in normal operation they are only loaded to 50%. This way when the tie breaker closes, the transformer that is now supplying both loads doesn't become overloaded and blow up in your face. The downside to main-tie-main is that the added reliability inherently costs more due to the system requiring larger transformers than a system that would not tie both circuits together.

Unfortunately, reliability costs money, and you'll need to oversize your transformers to add reliability to your system in a main-tie-main configuration.[/caption]

You can also reduce strain on each individual transformer when it is supplying both loads by adding external cooling to the transformers (like a fan cooling system). You can also simply accept that the transformers will have a reduced life in the event of a fault on a transformer or source.

You will not have just two loads in every case. In systems with multiple loads supplied by a single transformer, transformer size (and therefore cost) can be reduced by designing the system so that only essential operational loads (such as emergency lighting) are supplied power when the tie breaker closes.

Summary

For industrial power systems, a main-tie-main configuration is an extremely reliable power system distribution model, able to maintain power during a fault with little to no interruption. Unfortunately, this added reliability has a cost, whether in the form of larger transformers, extra cooling systems, or shorter transformer lifespans. These factors should all be considered when designing an industrial power system with main-tie-main in mind.

Arc Flash Mitigation techniques - Administrative

2016-07-29T10:00:00-03:00

The second to last line of defense with arc flash mitigation, according to the Hierarchy of Hazard Mitigation, is administrative controls. Administrative controls are implemented after a facility is designed and built, and equipment has been purchased and installed. What the administrative controls really boil down to is your electrical safety program. I'll break down what that is below.

Electrical Safety Program

An electrical safety program is a list of rules and procedures that must be followed by employees working with electrical equipment at your facility. You may already have a safety program in place, but it is important that you have a safety program that is specific to working on energized equipment. I've already written a series of articles to help you get started in putting together your own electrical safety program. I'll highlight a few key parts here with arc flash mitigation in mind.

Standards

There are a few major standards that need to be followed when working with energized equipment. The odds are high that you will need to adhere to one of CSA Z462 (if you're in Canada), NFPA 70E (if you're in the United States), or EN 50110 (if you're just about anywhere in Europe). Broader organizations that produce standards include OSHA, IEC, IEEE, and ANSI. This is in addition to any standards specific to your location, including provincial and state regulations. These standards will have specific guidelines for performing work on electrical equipment (both energized and de-energized), covering everything from work practices to label and PPE selection. All workers should be familiar with the standards. At the very least, the standards should be readily available to read and should be reviewed prior to any job on electrical equipment.

Job Planning/Maintenance Scheduling

Speaking of jobs, another administrative method for arc flash mitigation is job planning meetings. These should take place before a job dealing with energized equipment begins. In general, you want to make sure to plan your jobs and schedule maintenance around the critical operations of the facility. Proper planning can include work procedures such as Lock-Out-Tag-Out. You always want to try to schedule your work so that it can be done when equipment is de-energized. An arc flash cannot occur if there is no electricity. Proper scheduling also has the double whammy effect of ensuring that maintenance on one system does not impact the operation of another system. This leads to higher operational uptime for your facility.

Personnel Training

A major cause of electrical accidents, arc flash being no exception, is untrained workers wearing insufficient PPE. Well trained, well informed workers will be able to properly identify arc flash hazards and assess the risks, thereby reducing the likelihood of an arc flash incident occuring. Job specific training is mandatory before performing any new job. If the job is performed infrequently, establish a set period of time that can pass before it becomes necessary for an employee to repeat the training for that particular job. If it has been at least a year since an employee has performed a task, that employee must be trained again. Something to stress here is diligence: complacency with work can be just much of a hazard as anything else. Everyone should always be up to date on their training for any job.

Another thing that workers should be aware of is clear communication in the workplace. You can find our article on clear communication here.

Closing

Standards, scheduling, and training are just some administrative controls you can implement for arc flash mitigation. As always, thanks for reading!

Arc Flash Mitigation Techniques - Engineering

2016-07-27T10:00:00-03:00

If you can't eliminate the hazard completely, and you can't substitute the problem areas of your system with more appropriate methods, then engineering controls are your next best bet for arc flash hazard mitigation. There are many ways that engineering design can mitigate arc flash. You could even argue that every method of arc flash mitigation falls under the category of engineering controls. Today I'll talk about some of the big ones.

Protection Coordination Study

To begin the process of arc flash mitigation using engineering controls, the first thing to do is a protection coordination study. A protection coordination study is an essential part of arc flash mitigation because it lets you know how your protective devices will react to a fault. The most important part of the protection coordination study tells you how long a fault will be present before a device is tripped: arc flash incident energy is reduced by reducing the amount of time the fault is active. The protection coordination study will allow you to determine whether or not you need to change the the settings of your circuit breakers and relays. This is assuming that your circuit breakers and relays are digital and adjustable. If they are not, you might want to look at substituting them for newer parts.

Virtual Main System

I was going to try to explain a virtual main system, but the folks at Schneider-Electric have summarized it much better than I can, so I'll just quote them:

"A virtual Main consists of a digital relay and CT's added to the LV side of a substation transformer and wired to a Fault Breaking overcurrent device (Vacuum C/B) with the ability to use a "Maintenance Switch" to set a lower fault level trip or to use Short time Zone interlocking with the Secondary feeders to allow for faster tripping of the "virtual" main. "

All they're really saying here is that you have current transformers on the low voltage side of your transformer, and when the CT's recognize a fault they are wired to trip a breaker on the high voltage side of the transformer, protecting the entire circuit. You can find more information about maintenance switches and zone interlocking in our article on substitution.

Optical Relaying

Optical relays are a relatively new concept. Instead of tripping solely based on overcurrent, optical relays sense the light generated by an arc fault and use that as another trigger for tripping. An optical relay requires both overcurrent and the light generated by an arc fault to trip: the relay will normally not trip if no overcurrent is detected (but it will trip if there is high overcurrent but not light). These optical relays can have tripping times as low as 2.5 ms!

System Grounding

High resistance grounding limits single-line-to-ground fault currents to very low levels. These low current levels translate into low incident energy levels and therefore reduce the risk of an arc flash hazard occurring. From the IEEE Red Book (Std 141-1993, pg 367), "There is no arc flash hazard, as there is with a solidly grounded system, since the fault current is limited to approximately 5 A). You have to be careful if using this method of arc flash mitigation: high resistance grounding doesn't mitigate arc flash in the case of line-to-line of 3-phase-to-ground faults. Some more information about how high resistance grounding pertains to arc flash can be found here.

Location Design

Location, location, location. The location of equipment is very important. An arc flash causes rapid increases in temperature and as a result, rapid expansion of the materials that the electricity is flowing through. The explosive action of metals being vaporized and rapidly expanding is called an arc blast. Any equipment that has a high risk for arc flash should be placed in your facility in such a way that the effects of the arc flash incident are not magnified by location. For example, if an arc flash takes place in a small area, there is much less space for the energy to dissipate, and the effects of the arc flash will be concentrated. This is something that is more difficult to rectify after a facility has already been constructed, but is something to be considered during the initial design stages of any new building used to house electrical equipment.

So there you have it, five different techniques to consider when looking at arc flash mitigation from an engineering controls: protection coordination studies, virtual mains, optical relays, high resistance grounding, and location. This is by no means an exhaustive list, and an important thing to remember is that your arc flash mitigation techniques will be unique to your facility by necessity. As always, thanks for reading!

Arc Flash Mitigation Techniques - Substitution

2016-07-25T10:00:00-03:00

Substitution of Electrical Equipment

You can, however, replace equipment. After performing an arc flash study, you may discover that one of the reasons for high incident energy is that your equipment is old and out of date. If equipment is out of date, it must be replaced: replacement equipment could be selected for a number of reasons, including:

Selecting breakers and fuses with faster tripping times than those currently installed. As technology improves, newer protective devices generally trip faster than older ones. A faster tripping time leads to reduced arc flash incident energy. " Per the equations in IEEE Std. 1584-2002, arc flash incident energy varies linearly with time. If the duration of the arcing fault doubles, the available energy doubles; halve the duration and you cut the energy in half."
Arc resistant switchgear as a substitute for currently installed switchgear. Arc resistant switchgear contains the energy of an arc flash inside the equipment and directs it away from personnel.

Zone Selective Interlocking

Another way to reduce arc flash incident energy is by taking advantage of Zone Selective Interlocking (ZSI). ZSI allows your breakers to communicate with each other to provide the fastest tripping time possible. You can read more about ZSI here. An important thing to note is that in order to take full advantage of ZSI, you need to make sure your devices are coordinated.

Maintenance Switch

You can also mitigate arc flash hazards by adding an arc flash reduction maintenance switch to your system. The maintenance switch reduces incident energy levels on equipment downstream from the maintenance switch. The maintenance switch has its own analog circuit which is designed to trip faster than digital circuit breakers. More information can be found here.

To summarize, there isn't a whole lot of substitution that can be done when dealing with electrical power systems. However, you can still replace out of date equipment with arc resistant ones. You can also add equipment that can perform zone selective interlocking, and can add equipment with a maintenance switch to your system.

As always, thanks for reading! If you liked this article be sure to share with the buttons below and sign up for our newsletter where you will get these posts in your inbox and special offers. Be sure to follow us on Twitter and like our page on Facebook.

Arc Flash Mitigation techniques - Elimination

2016-07-22T10:00:00-03:00

Arc flash mitigation is important: to ensure the safety of a worker, every possible step must be taken to mitigate the arc flash hazard. Following the generally accepted hierarchy of controls, Elimination is the best way to mitigate an arc flash hazard.

De-Energize Equipment

When thinking about arc flash mitigation, this is the most straightforward way to eliminate an arc flash hazard. Simply de-energize all equipment that is being worked on. Without the possibility for current to flow, an arc flash incident cannot occur. All workplace electrical safety programs should stress that de-energizing equipment before work (such as maintenance) is a necessity. In order to ensure that you your equipment remains de-energized throughout the duration of the work and is not accidentally energized, you need to have appropriate safe working practices in place.

Lock-Out, Tag-Out

Lock-Out, Tag-Out (referred to as LOCO from here on out) is an excellent form of arc flash mitigation used to eliminate the risk of an arc flash incident occurring by ensuring that equipment remains de-energized while it is being worked on. LOCO requires that employees lock and tag the device being worked on so that it is impossible to accidentally turn the device on. The device can only be energized when all employees have removed their lock and tag and have confirmed that the device is ready to be energized again. This procedure does not work when it is necessary to perform work on energized equipment.

Remote Work

Sometimes equipment cannot be de-energized for work. When this happens, an arc flash incident cannot be eliminated entirely. With arc flash mitigation, what is most important is eliminating the risk of personnel injury caused by an arc flash incident. In this case it may be necessary to do work remotely. A few examples include:

Sensors can be added to equipment to monitor voltage, current, and temperature so that these readings can be observed on a computer instead of being observed by hand.
Switchgear can be closed remotely.
A remote racking system for racking circuit breakers will remove personnel from the arc flash boundary when inserting or removing breakers.

The best way to execute arc flash mitigation is to eliminate the hazard all together. You can do this by making sure equipment is de-energized for work using procedures such as LOCO. When it is not possible to de-energize, you can perform as much work as possible remotely using specialized equipment like sensors or remote racking systems.

What Can I Do With Incident Energy Studies?

2016-07-20T08:52:00-03:00

Today, I will outline three things you can do with a completed incident energy study. Completing these tasks is an important part of any electrical safety plan, and will reduce the risks to employees performing work on energized equipment. This will also reduce the risk of an arc flash incident occurring.

Identify Key Problem Areas

An incident energy study will show you where the incident energy is dangerously high in your facility. Now that you know the incident energy on a particular bus is high, you can analyze your power system with this information in mind, and try to answer the following two questions:

Why is the incident energy at this location so high?
Can the incident energy at this location be lowered somehow to provide a safer working environment?

Establish Working Boundaries and Select Warning Labels

Once you've answered the questions about your key problem areas, you might determine that the incident energy level cannot be reduced any farther. From here, what you can do is use the information in your incident energy study to establish safe working boundaries and acquire warning labels. The incident energy study should indicate the likelihood of an arc flash event occurring. Knowing the risks, you can assign appropriate working boundaries for the tasks involved with energized equipment. The incident energy study should have different "levels" assigned to each piece of equipment that is a part of the study. These levels correspond to recommended working distances, and you can use these levels to label all of your equipment so that every worker understands the risks of working on energized labelled equipment.

Select Appropriate PPE For the Job

Now you can use your newfound knowledge of the safe working boundaries to select the appropriate PPE for any job that takes place in your facility.

Determine working boundaries can also be used to determine PPE requirements. If for example you must work closer than the recommended working boundary, the incident energy study will recommend the level of PPE required for doing energized work at different working distances.

In order to determine what PPE you need, you'll have to use the relevant standards. CSA Z462 in Canada and NFPA 70E in the USA both have extensive tables describing what appropriate PPE is for the various levels of incident energy on a work site. It is important to also adhere to any and all local and regional standards for your area.

An incident energy study is required for determining safe working boundaries and PPE for the work site.

3 Causes of Harmonics on your power system

2016-07-18T09:47:00-03:00

But what causes harmonics?

Harmonics are caused by non-linear loads on a power system. Typically, electric current is produced as a sine wave: these loads draw power that is not a sine wave, and as a result, produce harmonics. |image1|IEEE Std 141-1993 (page 446-447) gives an excellent list of devices that might cause harmonics on your system:

Arc furnaces and other arc-discharge devices, such as fluorescent lamps
Resistance welders (impedance of the join between dissimilar metals is different for the flow of positive vs negative current)
Magnetic cores, such as transformer and rotating machines that require third harmonic current to excite the iron
Synchronous machines (winding pitch produces fifth and seventh harmonics)
Variable speed drives used in fans, blowers, pumps, and process drives
Solid-state switches that modulate the current-to-control heating, light intensity, etc.
Switched-mode power supplies, used in instrumentation, PCs, televisions, etc.
High-voltage dc transmission stations (rectification of ac to dc, and dc to ac invertors)
Photovoltaic invertors converting dc to ac.

A lot of these devices generate very small harmonics, so if you recently installed a large amount of them you should check to make sure that their harmonics aren't having a cumulative effect on your system. A few of the more important things to watch out for are the switched-mode power converters and resonance. The majority of this information comes from IEEE Std 141, which I cannot recommend enough to anyone who deals with power systems.

Switched-Mode Power Converters

Switched mode power converters come in two main types: single-phase converters, and three-phase, six-pulse converters.

Single-Phase Converters

Single phase converters use capacitive elements instead of resistive elements. This means that output voltages can remain stable for a large variety of input voltages and currents. This makes them ideal for silicon chip devices like computers. As long as the capacitor is at full charge, the device won't draw current, meaning that there are periods of time where no current is flowing to your computer. This gives it a very high third-harmonic component, which essentially acts as a very high neutral current. So if you've recently added a lot of computers to your power system, and are experiencing high neutral currents, this may be the cause. The third-harmonic can be as high as 81% of the value of the main current!

Three-Phase, Six-Pulse Converters

Three-phase converters are used extensively in variable speed drives and constant-voltage rectifiers. Similar to the single-phase converters, these have high sixth, ninth, etc. harmonic currents. In addition, they also have smaller harmonic currents for 5th, 7th, 11th, 13th, etc. harmonics. If not properly grounded, the 6th harmonic can produce a current through the bearings of a dc or ac machine.

Resonance

Resonance happens when the inductive reactance and capacitive reactance of your system are equal at a certain frequency. This becomes a problem if the reactance of your system is

resonant at the same frequency as a harmonic (in North America that means multiples of 60, or 120/180/240/300/360/etc.). There are two types of resonance: parallel and series.

Parallel Resonance

Parallel Resonance occurs when the inductive and capacitive elements are in parallel, and are equal at some frequency. If a harmonic shares this frequency, then the resonant circuit will be excited and cause a large amount of current to oscillate between the inductive element and the capacitive element. This can cause excessive voltage distortion.

Series Resonance

Series Resonance occurs when the inductive and capacitive elements are in series, and are equal at some frequency. If a harmonic shares this frequency, the series resonant circuit will draw all of the harmonic current, resulting in elevated current magnitudes across the circuit, as well as high voltage distortion between the inductive and capacitive elements of the circuit.

Hopefully now you have a better understanding of what can cause harmonics, and will be able to identify if any devices in your system are causing harmonics that need to be dealt with.

What is IEEE 1584?

2016-07-15T09:00:00-03:00

The latest revision of IEEE 1584 was released in 2002, and since then there has been much work on preparing and releasing a new version which with the increase in renewable energies and the necessary DC and larger capacitors, this new revision is greatly needed. But I'm getting ahead of myself.

IEEE 1584 2002 is

The Guide for Performing Arc-Flash Hazard Calculations published by IEEE Standards. This guide helps engineers, safety professionals, and manufacturers estimate the thermal energy that a worker would be exposed to in the event of an arc flash event. CSA Z462 and NFPA 70E both recognize this standard as an acceptable means of evaluating the risk associated to an arc flash hazard regarding the thermal energy.

IEEE 1584 Limitations

The 2002 version of IEEE 1584 does have some limitations, that at the made a lot of sense based on the installed electrical systems. They are:

Short Circuit Current - 700 Amps - 106,000 Amps
Three Phase Faults Only
Frequency 50 Hz to 60 Hz
Conductor Gap 13 mm to 152 mm
Sinusoidal AC only

Looking at the installed electrical power system, specifically non-utility, these limitations appear pretty minor. The majority of the installed industrial systems (commercial and residential included) in the world are AC at 50 or 60 Hz. The only major exception might be aluminum smelting or other ore processing.

The majority of arc flash events start as single phase in a piece of equipment, but propagate to 3 phase within a cycle.

Most of the arc flash events happen within electrical equipment with the gaps less than 150mm.

So in 2002 this made a lot of sense. However, the world has changed a lot since then. There is way more large DC installations in the form of battery storage, and solar installations, and added large capacitor installations both for VAR support and short term energy storage. These two installations are not covered in IEEE 1584-2002 and have very different arc flash characteristics.

Over the last couple of years a lot of research has been done to try and reduce the impact of these limitations. The last two IEEE Electrical Safety Workshops have had great papers presented on determining the arc energy of impulse arcs from large capacitor banks, DC arcs and high frequency arcs.

Other Limitations

You may have noticed above that I kept mentioning "thermal energy", well that is all that IEEE 1584 allows you to determine, the output of the equations are a energy density. The other hazards associated with an arc flash event include:

bright light
they are loud
physical and moving parts

The first two are pretty simple, but the physical and moving parts I will explain. You will read a lot about arc blast on the interwebs, and in reality its a red herring. There is no correlation between arc flash energy and arc blast energy. However, with the high currents during an arc flash event, there is a chance of cables and busbar whipping if they are not braced properly, and if the event happens at a height there is a fall hazard.

In 2015 there was a great paper presented where they were starting the development of a classification system that would take into account all the associated electrical hazards: A complete Electrical Hazard Classification System and its Application

Closing

Most of you will only be applying IEEE 1584 through the software you use to determine the arc flash incident energy, and won't need to know the complete ins and outs of how the standard is developed. IEEE 1584 is the best calculation method we have and as it develops it will be a much more completed standard.

Electric Shock and the Human Body

2016-07-13T10:00:00-03:00

A little while ago, I talked about two important components of electricity: voltage and current. Understanding both is key to understanding how to keep yourself safe around electricity.

Electric Shock and the Human Body

Electric shock is the physical act of electric current passing through the human body. The effects of electric shock can range from a slight tingling sensation, to immediate death. This handy chart is a good reference for how different types of current (AC and DC having different safety thresholds):

As you can see from the chart, 60 Hz AC is much more dangerous than DC or 10 kHz AC. This is because of the way the body works: to get a muscle to move, the brain has to send a tiny electrical signal along the nervous system to the muscle. The most important signals that we're concerned with are the ones being sent to the heart muscles: most people have a heart that beats at a frequency of about 60-100 Hz. If you want to test this, place your index and middle finger of your left hand on your neck, under your jaw and directly below your ear, then count the number of beats or pulses you can feel in a minute.

Why is low frequency current dangerous to the heart?

Because the heart beats at a fairly low frequency, low frequency current like the kind found in modern day power systems (60Hz in North America) is very dangerous because it can cause heart fibrillation. The heart is made up of a group of muscles that all have to work together to pump the blood through your body. Heart fibrillation is the medical term for when these muscles are no longer working together: your heart is off beat, and "flutters" or beats weakly but way faster than normal. This weakly beating heart can't pump blood through your body properly. The blood won't get to the lungs for oxygen, and the heart will quickly run out of oxygen and stop. The is known as cardiac arrest, or a heart attack.

DC and high frequency AC electricity are still very dangerous, but because they apply current continuously (or the current pulses so fast that your body thinks it's applying current continuously), it takes more current to override your body's natural electrical signals. Kind of like how your eyes can only see the world at 60 frames per second, and you just don't recognize faster speeds.

This is also why a defibrillator works: the paddles zap you with a big dose of DC current to stop your heart, but your brain is still sending signals telling the heart to operate like normal. If the heart is fluttering uncontrollably these signals from the brain wouldn't do much, but if the heart is stopped it just starts up again like business as usual.

Effects of electricity on other muscles

In addition to the nearly immediate death caused by electric current interfering with the heart, electric current can also activate your muscles, causing them to contract or flex. With DC, this usually causes one burst of muscle movement which could throw you away from whatever you're working on. AC, on the other hand, causes your muscles to continuously flex over and over again, which could cause you to spasm out of control. In both cases, the point where you lose control of your muscles is called the "Let-Go Current Threshold". For example, if you were shocked because you grabbed a wire, the current will cause your hand to grip the wire tightly and you won't be able to let go. The longer you are exposed to electricity, the more damage it causes, so this is clearly a very bad scenario. With both AC and DC, working from an elevated position (like on power lines) adds a risk of a fall injury if you lose control of your body from that high up in the air. If the muscles that move your limbs away from your body get activated first, you could throw yourself out of the bucket in the truck.

Electric Shock Burns

One last thing to worry about are electric burns. Just like a wire will break down due to heat when too much current moves through it, your body will burn during electric shock. The longer you have current moving through your body and the higher the amperage, the more severe the burns will be. One of the most dangerous parts of electric shock burns are that they burn you up from the inside out. Even after what seems like a non-fatal electric shock, the tissue inside your body could have been burned and scarred or killed. Dead and damaged tissue can all sorts of negative effects, including organ failure and amputation.

How can you prevent current from entering your body?

The human body has its own natural way to prevent current from entering it: skin resistance. The resistance of dry human skin can be as high as 100,000 ohms. This resistance gets dramatically reduced if the skin is wet

(sweat is a salty liquid, and water mixing with the salt on the surface of your skin will drastically reduce skin resistance as well). The resistance of the human body can also be lowered by any breaks in the skin (like a cut that hasn't healed yet). You want to provide the path of greatest resistance to the electricity in order to stay safe, and an open cut is a great, easy spot for current to flow into your body.

Another thing to keep in mind is that the breakdown voltage of human skin is 500 volts. This means that, at 500V and higher, the outer layer of the skin is destroyed by the high electrical energies. This results in drastically lower skin resistance.

And, as always, be sure to wear appropriate personal protective equipment (PPE) for the job. PPE is designed to keep you safe, and that extra bit of insulation could save your life.

So, in summary: stay dry, stay covered, and wear your PPE!

How to Protect Against Ground Faults

2016-07-11T10:00:00-03:00

I've already talked a bit about what grounding is, and what types of grounding are most common. What I haven't really talked about yet are ground faults and ground fault protection. While specific details will depend on the type of grounding that your system uses, some general principles can be applied to most systems.

What is a Fault?

A fault can be defined as any time electric current in a circuit is going somewhere that it shouldn't be. You can have faults anywhere in your system. For example, if electricity is arcing from one power line to another, that's a line-to-line fault.

The most common type of fault that occurs in electrical systems is a ground fault, where the electric current is running from somewhere in your circuit to the ground. Causes of ground faults could include, but are not limited to:

Faults caused by inclement weather. If a tree falls over in a storm and rests on power lines, you've now got a path from the lines through the tree to the ground.
Reduced insulation from age. If a cable is old and has been in use for a while, the heat from current passing through it could break down the insulation.
Reduced insulation from other sources. This could include moisture from high humidity or physical stress placed on power lines when they collect ice in the winter.
Excessive overvoltages can also cause faults. You'll remember in my article about different types of grounding systems, ungrounded systems had unnecessarily high overvoltages. This means that if you don't immediately clear the first fault, more faults could quickly develop!

How can I protect against faults?

The goal whenever you have a fault is to clear it (isolate the part of the circuit with the fault so that there is no power going through that particular line). In order to clear a fault, you first have to determine whether or not you have a fault, and then you have to determine where the fault came from.

To determine whether or not you have a fault, you can use a current transformer (CT).

A CT is hooked up to a meter that gives a reading based on how much current is flowing through the primary side of the transformer: 5A of current in your CT might mean that you have 500A of current flowing through your ground line. So as soon as you have a fault, the meters hooked up to your CT will let you know that your ground line is getting current when it really shouldn't be.

You want to have multiple CTs attached to different points in your circuit. For example, most if not all substations in your electrical power grid will have CTs and PTs (potential transformers that measure voltage differentials) so that if anything goes wrong on the grid, the power company can isolate the problem right away.

Once you know that you have a ground fault, you've got to clear it. You can do this by using a selection of relays, circuit breakers, and fuses.

A relay is a device with adjustable settings that is used to determine whether or not to trip (open) a circuit breaker. Because the relay is the device that makes the decision of whether or not to cut the power to a portion of thecircuit, it must be able to activate blindingly fast, on the order of milliseconds. This is to make sure that when a fault occurs, the section of the circuit with the fault is isolated as soon as possible to prevent harm to people and damage to equipment.

A circuit breaker is a pathway that is mechanically forced open when too much current passes through it.

A fuse is essentially a wire that is designed to be destroyed when a certain amount of current passes through it. The difference between a fuse and a circuit breaker is that when a fuse is activated, it is destroyed and has to be replaced. When a circuit breaker is activated, it can be re-set by physically closing it again.

Protection in Action

In a typical scenario, a CT or PT senses current or voltage along one of your power lines. If there is a fault and the current or voltage level increases to an unacceptable amount, the relay opens the circuit breaker and isolates the area of the circuit. There may also be fuses somewhere in the system that will burn out and instantly open the circuit if too much current passes through them.

One important thing to be sure of is that your protection devices are all properly coordinated with each other. You want to be sure that a fault at one end of your system does not completely take down your whole system. Your

relays should be connected in a network. If one relay trips a breaker, it should be sending a signal to all relays closer to the source, telling them not to trip because the fault has been taken care of. This is another reason that relays need to be fast: if your devices don't work fast enough, you might end up with multiple relays unnecessarily tripping circuit breakers. Unwanted circuit shutdowns cost time and money to fix.

You can even observe ground fault protection in your home: if you live in a newer home, you should have some ground fault circuit interrupters (GFCIs) installed at your power outlets. These also monitor for current imbalances and will shut off the power to that outlet if it detects a fault.

So, to quickly recap:

A ground fault is an unwanted electrical connection between a line and the ground. It can be caused by insulation breakdown, bad weather, or physical stress.
You can protect against faults using protective devices, including CTs, PTs, relays, circuit breakers, and fuses.
Your protective devices must be coordinated for the best protection and efficiency in the case of a fault

Equipotential Zones: Keeping you safe during energized work

2016-07-08T10:00:00-03:00

If you are working on high voltage equipment (like power lines), you need to be sure that you are protected from shock hazards that could arise from an unexpected fault. Grounding makes sure that current will be directed along the ground or neutral wire in a system during a fault, but there is still the risk that if you touch the live wires, the current could travel through you into the ground instead of through the neutral line.

How can we stop the current from flowing in to your body at all?

We know that electrons need a voltage to flow: without a difference in electric potential energy between two points, there is no voltage, and therefore no current. Grounding can be used to create an “equipotential zone”.

What is an Equipotential Zone?

This matches all the objects in the zone to the same potential, so the voltage between any two objects in the equipotential zone is zero.

Let me take a step back and explain. The reason this works is because in mains electric systems (AC power being delivered from the power plant to your home, or office, or warehouse, etc.), they use the ground in the earth as their “reference voltage”. So all voltages are calculated considering the ground as “zero volts”. What this means is that when you hear people talking about 120 volts in your house, they're saying that the difference in voltage between the wires in your house and the ground is 120 volts.

Normally, if your system is balanced 3 phase power (like properly operating electricity in your home), there will never be any current flowing into your neutral wire: the potential of the neutral is the same as everywhere else. This changes if there is a fault. A fault is just a low resistance (meaning high current by Ohm's Law) path for the electricity to travel back to its source (since the circuit has to be complete for current to flow).

If there is a fault somewhere in your system from a main line to some metal surface not designed to carry current, you now have a path through the ground for the electricity to go to. This means that if, for example, you touch a metal door frame, electric current could go through the door frame, to you, to the ground.

We can prevent this by creating an equipotential zone

An equipotential zone is created by grounding all of the metallic surfaces that are not part of your electric circuit. For example, in buildings, in addition to having the ground wire connected to the earth, the grounding wire is also connected to all of the structural metal, all of the metal water pipes, all of the metal everywhere. So, if there's a fault, it's not as big of an issue because instead of raising the doorframe voltage relative to the ground, you'e raised the voltage of the whole building, including the ground, to match the system voltage.

You've experienced this type of grounding, called “bonding earthing conductors” if you've ever had to jumpstart a car: the negative jumper cable on the side of the dead car is always connected to the metal of the car frame instead of the car battery itself, right?

What if the neutral pathway to ground is lost?

By now you'ee probably wondering, what happens if the pathway to ground is lost, or broken? With your neutral wire no longer directing the current to the ground, you would normally now be in danger of the current traveling through you. However, you are still in an equipotential zone: now that everything around you has been brought to the same voltage as the power lines, there will not be a voltage difference between any two points that you can possibly touch. No voltage difference means no current, and not current means no danger!

Of course, this is why bonding earthing conductors are so useful: if all of the metal in a building is connected electrically, including water pipes and structural steel which extend into the ground, then your whole building has essentially become a giant ground rod and you actually never lose your path to ground!

Three Different Types of Grounding

2016-07-06T10:00:00-03:00

Today I'm going to give you a brief overview of three different types of grounding systems that are important.

These three systems are:

Ungrounded Systems
Resistance Grounded Systems
Solidly Grounded Systems

I've already talked a little bit about what grounding is, including giving a brief overview of why we do it and what it's used for. If you haven't read that article yet, go give it a read before continuing.

Finished reading about what grounding is? Alright then, let's get to the meat and potatoes of today's topic.

Ungrounded Systems

“Whoa, hold on”, you might be thinking, “We just finished reading about how important grounding is for safety! Why would we have ungrounded systems?” The answer is that we shouldn't really have ungrounded systems, but they do exist and they do have their purposes.

You see, an ungrounded system isn't really ungrounded. Electrically, your system is connected to ground through the capacitance between the lines and the earth, so you can say that it's a capacitance grounded system. We just call it ungrounded because of convention, and because there isn't a direct physical connection between any of your power lines and the ground.

Advantages

There are a few advantages to having an ungrounded system. The first is that since your system is never physically connected to the ground, you have negligible ground fault current. For example, in a 3-phase system, because all of the ground fault current is capacitive, when you have a single line-to-ground fault in an ungrounded system, the current and voltage you would lose is negligible, and is instead carried by the other two lines. This allows you to continue operation unimpeded during a single line-to-ground fault.

The other big advantage is that because of the negligible ground fault current, special ungrounded systems can be used to minimize shock risk to people. An excellent example would be medical equipment in a hospital: a patient is directly connected to the machine, and if a fault were to occur, electricity might be able to flow through the patient and into the ground. Because the ground fault current is negligible in an ungrounded system, no power current will pass from the machine through the patient into the ground.

Disadvantages

Of course, the disadvantages of an ungrounded system are obvious. If there is a fault, you are now using two wires to carry an amount of current that was allotted for three wires: the increase in current and voltage will jack up the heat, and the extra heat will wear out your insulation much faster. Worn out insulation could lead to unnecessary damage to your electrical system, particularly at motors.

The other big disadvantage of an ungrounded system is that it is incredibly difficult and time consuming to locate any faults. Each line must be tested individually, which is a very slow process that completely interrupts service. The opportunity cost of a fault in an ungrounded system is very high.

Ungrounded systems were the norm back in the 40's and 50's, but because their disadvantages outweigh their advantages in most scenarios, you won't see too many new ungrounded systems today.

Resistance Grounding

Resistance grounding is when you have a connection between your neutral line and the ground through a resistor. This resistor is used to limit the fault current through your neutral line: if your voltage doesn't change, then your current is dependent on the size of the resistor according to Ohm's law (V=IR).

Advantages Over Ungrounded Systems

Because the current in the neutral is controlled instead of negligible, system overvoltages are also controlled. This reduced current and reduced overvoltage means reduced heat, which keeps the wear and tear of your electrical system to a minimum. This is especially important for keeping your motors safe, since the reduced current will not damage the magnetic iron of the motor (which is costly to repair). The reduced currents also reduce the risk of shock and arc flash/blast hazards.

There are two types of resistance grounding: high resistance grounding and low resistance grounding.

High Resistance Grounding

High resistance grounding is typically used to limit ground fault current to < 10 amps. The low ground-fault current also means that, just like an ungrounded system, you can continue to operate the system on a single line-to-ground fault. The low current will typically not trip your protective devices during a single line-to-ground fault.

Overall, you want to use high resistance grounding when you need low fault current and still want to operate with a single fault. High resistance grounding is typically seen in retrofits of previously ungrounded systems in addition to new systems.

Low Resistance Grounding

Low resistance grounding typically limits ground fault current to between 100 and 1000 amps. This offers a similar advantage to high resistance grounding in that you can control the ground fault current, which means you can design your system to withstand the currents without damage.

Low resistance grounding systems have the benefit of tripping your protective devices when there is a fault. Their purpose is to immediately cut the power to the circuit, and so unlike the high resistance grounding systems, a low resistance grounding system will not maintain operation during a single line-to-ground fault.

Low resistance grounding also reduces overvoltage, and is used in medium voltage systems of 15kV or less, typically where big generators/motors are used.

Solid Grounding

Solid grounding is what you get when you connect your system directly to the ground, without any sort of resistance in the way. The ground is typically connected to the system at a neutral point, like the neutral terminal of a generator or transformer.

Pros and Cons

Solid grounding, like resistance grounding, can greatly reduce overvoltages in your electrical system. However, solidly grounded systems have the potential to have huge amounts of ground-fault current. As a result, solidly grounded systems cannot operate with a ground fault (since all of the current in the system is going from fault to ground). Solid grounding has two main uses:

In systems with voltages of 600V or less, solid grounding can be used if it is not necessary to maintain operation of a faulted circuit.
In systems with voltages of 15kV or greater, solid grounding can be used if high ground fault currents are desirable of any reason, such as quick ground fault detection (since the high current will most definitely trip protective devices).

Recap

You can use ungrounded systems when you want to have negligible ground-fault current.
Resistance grounding offers the advantages of ungrounded systems without the risk of large overvoltages.
Solid grounding reduces overvoltages but has high ground-fault currents.

At the end of the day, the type of grounding you use for your system will depend on which type of grounding best suits your needs and budget.

What is Grounding?

2016-07-04T10:00:00-03:00

What is grounding in an electrical sense? Anyone with a little bit of a background in electronics will tell you that grounding is something you need to keep your circuit safe and it keeps the electrical parts of your circuit from blowing up. But what is it, exactly?

Grounding is a connection between an electrical circuit and an arbitrary reference point.

Grounding is a method of protecting your electrical system and the people using it from harm by setting a known “reference” point for voltage. When you hear someone mention ground, you should ask them to clarify: is it the reference voltage, or is it earth itself? Or is that both? In order to explain grounding, we need to know a little bit about voltage and current. Before you continue, read our article “What is electricity?” It has a bunch of the background knowledge that I'm going to assume you know when I talk about grounding.

Grounding: A History

The earliest instance of grounding that I can think of is when Benjamin Franklin invented the lightning rod.

A lightning rod is a metal rod attached to the top of the house, connected by a wire to another rod stuck in the ground. When lightning would strike, it would seek out the rod (since the rod has a lower resistance than the rest of the house) and electricity would flow into the ground. This prevented houses from burning down when struck by lightning, which can generally be considered a good thing.

If a lightning rod can be seen as the first real instance of grounding, then we can look at grounding as one part of the overall electrical protection system for your circuit. So in order to keep things safe, you need to figure out a way to create a pathway for the electricity to travel that has less resistance than your body, fragile circuit components, and building materials.

In the event that something goes wrong in your circuit for whatever reason, you need to direct the electric current along a very low resistance pathway. We've already talked about how to figure out what resistance is, but what kind of wire would have a low enough resistance to draw all the current?

Why not use the ground itself?

Think about it: use the planet earth as a conductor. Not only does the electricity not have very far to go to get in to the ground, but it also has a HUUUUUUUUUGE cross sectional area, meaning it has very, very little resistance. Electrons always want to go to the place of least resistance, which makes going into the ground their favourite place.

The lightning rod used this concept to great effect, and modern day power companies do the exact same thing. This also doubles as a useful way to complete your circuit: by using the earth itself as your ground wire, you can be sure that every point in your circuit (which in this case is the entire power grid) is connected to the same reference point. This means that when we now talk about voltage (for example, the 120V wires in your house) we know that we're talking about it with reference to the voltage of the ground itself. There are 120V between the wires in your house and the ground you're standing on, there are 1000kV between the overhead power lines and the ground, etc. What this also means is that the current in your circuit now has a clear and easy return path to its source: the current can just flow into the ground near, for example, your house, and travel back through the ground to the generators in the power plant.

But isn't the system still unsafe?

You might see the new problem with that: if electrons want to go in to the ground, how do we get them there safely? If you are standing on the ground and you touch a wire with electric current moving through it, won't the current just go through you and into the ground, instead of going through the wire?

Current flows through all available pathways at once. This means that even if the ground wire path is the least resistive path for current to flow through, you could still harm yourself by adding yourself to the circuit when you touch it (making a path from the wires through you to the earth). Initially, I said that grounding was to keep your circuit safe, and I wasn't lying to you. The reason grounding keeps the circuit safe is that grounding makes up a part of your circuit's protection system.

Most circuits are designed so that when there is a fault to ground in the circuit, the majority of the current will flow through this fault, into the ground wire, and into the ground. Because we know where the current will flow, we can put protective devices along the ground path in such a way that as soon as the fault occurs, the protective devices (such as a fuse or a breaker) are tripped very abruptly. When this happens, the complete pathway for the circuit is broken, and current cannot flow. If current can't flow, we have no voltage difference, and if we have no voltage difference, we have no real danger. This is the most common way that grounding protects circuits: it forces protective devices to turn the circuit off ASAP.

In order for grounding to work in tandem with your protection system, you need to know how much current can be expected to flow through your ground wires in the event of a fault. You can figure out what amount of current to expect by performing a protection and coordination study. This will let you pick the appropriately sized fuses or breakers.

Wrap up

In summary, we can think of grounding as a circuit protection technique that doubles as an easy way to measure voltages. Electrical grounding can be:

A common point of reference in your circuit that is used to measure all voltages
The earth itself, when the common point of reference is stuck into the ground that you walk on
A technique used to direct fault current along a low resistance path to protective devices that will immediately turn off your circuit
All of the above

Hopefully you've enjoyed reading this article, and now know a little bit more about grounding.

Executing a Power System Study at a pulp and paper mill

2016-06-07T08:00:00-03:00

There are a lot of different ways to successfully complete any power system study, but the best for any pulp and paper mill is likely a hybrid, with a lot of the time consuming activities being down with mill staff. The advantage of this system, is that when you have the scope of the project outlined, you can start gathering the necessary information before engaging a consultant.

Here are three thoughts around data gathering (the most costly part of a power system analysis) when you decide to get started with a power system analysis project at your pulp and paper mill.

Data Gathering

Typically the most time consuming part of developing a complete power system model is data gathering. This is something that is best done by the people that know the facility the best, and have the best grasp on the electrical safety program. A lot contractors will want to bring in outside help, but if the system is under operation this will increase the risk of an unscheduled shutdown as these inexperienced contractors are rooting around in MCC buckets trying to find wire sizes.

1 Start off with drawings

Most of the information needed for a power system analysis, especially the short circuit study, can be found in the existing drawings:

single line diagrams
motor elementaries
General Arrangements (cable lengths)

If you couple this with other support documentation like cable lists and relay setting sheets, the biggest chunk of the information will be done. However, this doesn't mean you don't have to get out into the field and verify everything. Unfortunately, drawings and support documentation don't have all the current information, some examples that may be missing are:

fuse manufacturer
transformer impedance
cable length

These will need to be as-built in the field during the data gathering process, and recorded. As one of the deliverables, the affected drawings will be updated when the report is completed.

2 Ideally completed by the owner's staff

Based on the age and complexity of most forest product plants, we recommend that plant staff (preferably electrical workers) gather the information over a reasonable period of time. Electrical shop workers are routinely all over the mill, and adding a requirement to as-built information as a routine task will limit the back work, and is a good habit to be in for any case.

Accurate drawings shorten unplanned shutdown times.

One of the side benefits of having current drawings is when something does go wrong, you can troubleshoot from a drawing, and then implement solutions. If you are always worried the drawing is incorrect you ended up drawing out the circuit on a napkin (or any other scrap of paper) while you troubleshoot, all the while 5-10 people are looking over your shoulder "helping".

3 Best done during shutdowns

Speaking of shutdowns, opening up switchgear and MCC buckets is best down during planned shutdowns. Partial shutdowns are a normal part of a pulp and paper mill, by ensuring there are enough electrical workers on staff during the outage to support the data gathering effort.

It is important to gather the data in a safe manner, ideally with the equipment de-energized. A shutdown allows you to access a large majority of the equipment de-energized, without affecting the rest of the plant process. While inspecting may not be a "working on" type task based on your energize work permit, finding some of the information may require manipulating wires, etc. For example, how often do you think you will see the wire gauge in a MCC bucket?

Next Steps

A power system analysis report is a critical tool for any pulp and paper mill in today's lean wood products economy. If you are interested in learning more about power systems you can join our Power System Newsletter here, when you do we will send you a technical spec that you can use with your next RFP.

If you have any questions give me a call or send me an email, you can find my contact information here. If you liked what you read, signup for our newsletter below.

4 Ways to save money with a power system analysis at your pulp and paper mill

2016-05-31T09:00:00-03:00

Sometimes it seems that the number of requirements for running a plant keeps going up, and regulations keep changing cutting into the bottom line. This is how a lot of clients I have worked with in the past have approached getting a power system analysis completed, they needed labels on their equipment to satisfy the requirements of CSA Z462 and NFPA 70E, so they needed an arc flash study. It was an expense, nothing more.

However, if you define the scope (the first step in performing a power system analysis) smartly, you can duplicate effort without duplicating cost, and use the report to make smart decisions that will either save money immediately or identify capital projects with very fast payback.

1 Reduced number of Electrical Safety Incidents

According to NFPA (source-pdf) the average shock or arc flash injury event can cost $80k in direct costs, if indirect costs are included this can be much higher. However, according to that same paper there are no valid ratios to estimate this.

With a power system analysis in hand, an effective electrical safety program can be developed that will directly affect the number of these incidents. The number of these incidents are typically very low, however the high cost of a single incident will pay for the power system analysis and electrical safety program many times over.

2 Better preventative maintenance program

Competitive pulp and paper mills have at least a preventative maintenance program, and a lot are moving to a predictive maintenance program. The most important part of these programs, like a valid power system analysis, is the quality of input data. When going through the process of validating all the input data for a power system analysis, it would be a simple matter of gathering the information for your maintenance program without duplicating effort. It is likely the same staff that will be doing the work in anycase.

With better information, including short circuit values, expected load flow voltages, etc, you can feed this information into the maintenance program and understand when equipment may fail, allowing you to plan its replacement without affecting the process.

3 Power Quality Improvements

When going through the system and gathering all the necessary input data for the incident energy study, you have all the inputs for proper load flow study, and all you need is some existing load information that can be gleaned from the power meters throughout your mill.

This is where you will see an opportunity to get the most value from the power system analysis. Like most industrial plants you are likely charged:

a energy fee (MW-HR),
a peak charge (rolling MW) and
sometimes a power factor charge.

You can minimize your power factor and energy fees by making sure that you are running your system as close to unity power factor as possible. With a proper power flow study, you will be able to identify areas within you plant that would be best suited for adding power factor correction capacitors and quickly identify the potential payback.

4 Update Drawings of the System

Finally, and likely an over-looked part, is that you will have updated drawings as part of your power system analysis that are very accurate, current, as-built conditions. These drawings are now trusted inputs for any capital or maintenance projects that may take place in the future.

One of the biggest risks to integrating into any existing system, is the quality of the existing documents, and the cost of having a consultant on site developing as-built drawings will increase the cost of a small project quickly. Having these drawings on hand, and assuming you have a document control procedure in place, the consultant replacing a motor or adding a new system will have the best information starting, reducing the design time, construction issues, and start-up concerns.

Next Steps

If you like what you read consider joining our newsletter where you will get every post in your inbox at the start of the month. You will never miss a thing. If you would like to learn more about how a power system analysis can help you manage your system better and safer, contact us here, or visit our services page here.

Getting a Cement Plant Power System Report Completed

2016-05-24T08:00:00-03:00

Cement plants have a cyclical profile where they are producing product before the building cycle, and full out throughout the building cycle (spring to winter) to keep with demand, then annual maintenance in the winter until it is time to get started again.

Hybrid Approach

With leaner engineering groups in all of industry, we recommend a hybrid approach with you using internal electrician and engineering resources to gather the data needed for the complete power system analysis. If there aren't any power quality concerns at the plant, or your power system study isn't current we recommend getting started with:

Short Circuit,
Protection Coordination, and
Incident Energy (Arc Flash)

Recommended Scope of the Power System Analysis

The cement plant power system is large and complex, with a range of voltage levels from 100kV to 120/208V. If you are starting from scratch at the plant, or if you (or the person running the project) don't have a lot of experience with power system studies, it is best to chunk out the system in bit sized chunks. But make sure that how you break out the system is done in such a way that you will have a useable product at each stage.

How much of the Cement Plant Power System

For example, we recommend that you model the entire MV system, from the incomming from the utility down to any 5kV that is on the plant. This will allow you to address all the large motors, generation and utilities on the site that will account for the majority of the fault availability. Depending on the size of the system and budget, this may be all that you get done in the first round.

The next step is to pick one of the feeders in your system, or a single area of the plant and complete the model (and report) to the 600 V (or 480V in the US) system and include all motors 25hp and over, and to the secondary of any 120/208 distribution panels. Motors less than 25hp will likely not affect the available back feed into a fault, and therefore can be neglected.

120/208V system

The 120/208V distribution panels may be contentious and not needed at your facility. I have typically neglected them in the past, however there are still a lot of electricians that will work on a panel at this voltage energized without a second thought, I have started recommending labeling these panels with full Arc Flash/Shock Warning labels with the intent of raising the awareness that the hazard is still present, and PPE is required.

Electrical Safety Program

In the 2015 revision of NFPA 70E mining was removed from the exceptions, and MSHA has endorsed NFPA 70E as the standard for PPE selection with regards to arc flash. What this means to you is that NFPA 70E is the de-facto workplace electrical safety standard for cement plants.

Having a current (every 5 years) arc flash analysis, which includes a power system study, is a requirement for any successful electrical safety program.

Getting Started today

If you aren't in a position to get started with a power system analysis at your cement plant today.'

If you are ready, to go NOW, give us a call and we can provide a free quote and execution plan to ensure that the report meets all operational needs of your engineering and safety groups.

As always, if you have any comments or questions, don't hesitate to give me a call.

Regards,

3 Ways to get a Power System Study Completed

2016-05-17T08:29:00-03:00

You already know why you need a power system study at your plant, but what about actually executing the project. There a three basic way to approach getting a power system analysis completed:

Completely In-House
Completely contracted out
Hybrid of both

These have their pros and cons, and depending on the size and complexity of your company and system the method that is chosen may be obvious. Below is a brief description of each method, including a couple pros and cons of each.

1. In-House

When you complete the power system analysis in-house, you will have the advantage of being in complete control of the end study, and as a company you will have a better understanding of the status of the power system as a hole. This is one of the less talked about advantages of having a power system analysis prepared, it gives you the opportunity to double check all your drawings and understand any oddities throughout.

Completing the power system analysis in-house assumes you have the resources within your team, including

Skills - Someone has done these before and knows how to do this one
Tools - The necessary software is in-house and there are staff trained in using it.
Time - There are resources to complete all five steps to get it done.

2. Outsourcing

When you outsource the power system analysis to your favorite consultant, it can be a simple matter of writing up a scope and walking away.

This will greatly reduce the drain on internal resources, now you only need to monitor a contract and review the reports. However, when you do this you also lose some control and add to the monetary cost of the project greatly.

In summary, outsourcing the project will likely reduce you direct input greatly, while increasing the project cost.

3. Hybrid Model

A hybrid model is one that keeps your involvement high, while outsourcing the project parts that you don't have the resources to complete, whether its time or skills. For example, assume that your company has the resources to gather all the data for the project, but doesn't have the necessary software or anyone available that has experience in preparing a power system analysis. In this case you could outsource the model development, studies and report (steps 3-5) and prepare the scope and gather the data using company resources (steps 1 and 2).

This model has the advantage of ensuring that the data used in the analysis is accurate to site conditions as your personnel will know the site better than anyone, the cost will be kept under control as data gathering is one of the most tedious and expensive parts of the project when completed by an outside resource, and the study results and recommendations will be accurate and actionable because you had an experienced consultant prepare them for you.

The hybrid model allows the power system analysis project execution to be:

Good input data - know one knows the facility better than the people who operate it day in and out
Cost Effective - consultants doing what they do best, and company resources gather the necessary data
Accurate and Actionable - experienced consultants who have the tools, and training can provide the best report.

What we think

In most cases we will always recommend some type of hybrid model, but the split will always be different and dependent on the resources of the company that we have engaged with to complete the analysis. By using a hybrid model you will be able to leverage our strengths in power system modelling and analysis to produce a great product, while using your internal resources to gather the necessary input data to keep the costs low (and value high) without sacrificing quality.

If you have a project that you want to talk to us about don't hesitate to use the contact page.

What is Arc Flash? (and Why You Need to Label)

2016-04-19T00:00:00-03:00

Arc Flash Hazard is one of the three hazards that are directly associated with electricity, the other two being shock and arc blast.

CSA Z462-15 defines Arc Flash as:

a dangerous conditions associated with the possible release of energy caused by an electric arc.

When there has been a breakdown in equipment insulation, whether from equipment failure or an electrical worker coming into contact when working on energized electrical equipment.

What Arc Flash Looks Like

https://youtu.be/CP8ffmjZ9K4

The video above is an example of an arc flash in a 100A disconnect, it demonstrates the immense energy released and a typical application.

3 Side Benefits of an Arc Flash Study

There are tons of reasons to have a current Arc Flash Study, and an Electrical Safety Program, here are three side benefits that you may not have thought of include:

As-Builts - When was the last time you incorporated all the redlines associated with your power system?
Enclosure Audit - Are you sure all your equipment enclosures have their doors secured? Are there latches missing?
Document Switching Configurations - Knowing the valid switching configurations for the facility is critical for the study, but not every plant has these written down for the operators.

Labels

The Canadian Electrical Code (rule 2-306) requires labels on all electrical equipment that may require energize work to have a warning label that an Arc Flash and Shock Hazard is present. However, that alone doesn't provide enough information to ensure that the electrical worker opening that panel can select the appropriate PPE. Below is an oversized example of a typical label we would recommend.

It includes all the information that is recommended by CSA Z462 and is easily read and can be audited without much effort. The top warning and first header line is all that is required by the Canadian Electrical Code, the remainder of the information provided allows a trained electrical worker to select the appropriate PPE for the task at hand.

Next Steps

Here I outlined a couple of simple reasons why you should have a current Arc Flash Study - or complete Power System Analysis - for your plant.

If you have any questions about what you read here, please don't hesitate to contact me through the contact page here.

Regards,

Jeff MacKinnon, P.Eng.,PE

What is CSA Z462? (Plus: 2 Huge Assumptions You Might Be Wrong About)

2016-03-15T08:00:00-03:00

Laws vs. Standards: Who Cares?

Last week I talked about how CSA Z462 may not be written law in Canada, but it is still the industry standard

So - if there is an incident at your workplace, it will be the standard that the courts will use to evaluate the workplace electrical safety program. Simple and to the point, yes? Now think back to an occasion (pick one!) where you or someone you know somehow diminished or in some other way equivocated by using the "well - technically it's not the law" semantics-laden argument for self-serving (not safety-minded) reasons. Bottom line is: who cares? It's still the standard the courts are going to hold you to.

Today I will explain what CSA Z462 is, and a couple of ways that it can be applied so that you can ensure your employees will go home with no injuries every day.

Before getting into that though - let's deal with the elephant in the room. Let's talk about these mistaken notions you so often hear at outside training courses, youtube and from PPE manufacturers and clarify what CSA Z462 is not.

CSA Z462 is NOT an electrical safety program

Say it again. This should be a nice, deep cleansing breath for you - "CSA Z462 is not an electrical safety program." There. Doesn't that feel better?

The definition of a square can fit for a rectangle because it is a quadrilateral with 4 right corners. However, the definition of a square does not fit for a rectangle because a rectangle doesn't have four equal sides. Bearing this in mind, if I ask if I can see your electrical safety program, don't tell me "We follow CSA Z462" and think that'll be the end of it. There's much more to the definition of an electrical safety program than the standard that it might happen to include. You're right insofar as you think that:

CSA Z462 is what best sets up the framework for an electrical safety program
Its what lists the requirements that are needed in an Electrical Safety Program in general terms

BUT you're wrong in applying the definition of the standard (rectangle) to a program (square) that has more specificity and detail required. Consider that the standard does not have:

A comprehensive list of tasks
Well defined and documented procedures
Risk analysis on tasks (and other things) needed at your plant or facility.

If you're just getting started, or if you're just realizing that perhaps your Program could use a little TLC, it doesn't have to be that daunting of a task.

Define the specific tasks that everyone will be doing
Define the general roles and responsibilities of those involved
List out all the hazards related to those tasks
Develop a consistent risk analysis for each of those tasks and the corresponding hazards.

Depending on your capacity you may find that outsourcing this work is a better path, but if you do, be sure you clearly lay out your expectations for what you will get based on the above.

CSA Z462 is NOT an Arc Flash Standard

To be sure, one of the hazards that will be evaluated is in fact the Arc Flash Hazard, but that's but one component (albeit an important one) and doesn't "ipso facto" make it the standard itself. This is a subtle yet critical error in logic that many firms make, and many find out only after it's too late and they find themselves in a world of trouble.

This misconception likely owes it's origin to when the 2006 Canadian Electric Code came out. At the time, it stated simply that Arc Flash Hazard Labeling was needed on electrical equipment. Six years later the first edition of CSA Z462 was released with an emphasis on arc flash hazard analysis.

CSA Z462 is on whole Workplace Electrical Safety, not just the single hazard of Arc Flash

What CSA Z462 IS

So you get the gist - the standard is more than the sum of some of it's more familiar parts. Titled the "Workplace Electrical Safety Standard", it deals with shock, lock-out-tag-out, and much more. CSA Z462 outlines the various hazards that may exist at your facility, specifically shock and arc flash, and provides suggestions as to how to control these hazards. The standard outlines what the committee believes is required to establish a electrically safe work environment for all workers, but specifically electrical workers.

CSA Z462 states that the company shall have an electrical safety program and outlines what this includes in the appendix. It also states that if there is to be energized work, an energize work permit shall be developed to outline the hazards that are associated with the work at hand, including shock, arc flash, other energy sources, etc; the risk analysis and the control methods used to reduce the risk of injury to the worker and any employees that may be in the area.

In future posts we will detail each of the chapters in CSA Z462 and discuss the "Why" behind some of the statements in there. It is always more important for the employer and employee to understand the why. With the why the worker and employer can understand the controls that are put in place and have a greater respect for them

CSA Z462 is not law. But...

2016-03-08T08:25:00-04:00

There is a misconception that I hear every month or so when talking to clients and other engineers, it is that since CSA Z462 isn't written directly into the law of the land that it doesn't have to be followed.

Well, they are right that it isn't written in the Provincial Regulations, with the exception of BC where it is referenced as an acceptable standard, but they do reference the Canadian Electrical code CSA C22.1, and C22.1 references CSA Z462.

For example in Nova Scotia Occupational Health and Safety Act paragraph 120 (1) states:

An employer shall ensure that an electrical installation is designed, installed, assembled, operated, inspected, serviced, tested, maintained, repaired and dismantled in accordance with the latest version of CSA standard CSA C22.1, “Canadian Electrical Code Part 1”, Safety Standard for Electrical Installations”.

When you open the Canadian Electrical Code Part 1 (CEC), there are two rules in Section 2 that stand out:

Rule 2-304 (1)

No repairs or alterations shall be carried out on any live equipment except where complete disconnection of the equipment is not feasible.

and Rule 2-306 (1)

Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centres that are installed in other than dwelling units and are likely to require examination, adjustment, servicing, or maintenance while energized shall be field marked to warn persons of potential electric shock and arc flash hazards.

These rules both point to appendix B in the standard with notes on the rules that point the reader to CSA Z462 as an acceptable method to meet the intent of these rules. To my understanding this hasn't been tested in the court of law, but it would be negligent not to use CSA Z462 as the minimum standard when developing a safety program in your company.

Not only CSA Z462

That doesn't meant that CSA Z462 is the only standard that can be used, NFPA has a comparable standard numbered 70E that says all the same things as CSA Z462, but in standard units vs metric.

Using Nova Scotia as the example, using the current version of CSA Z462 (or NFPA 70E) as the standard when developing your electrical safety program is the most prudent means to ensure the safety of your employees and compliance to local law.

In Summary

CSA Z462 is the accepted industry standard regarding electrical safety in the workplace, and the 2015 revision allows tight integration into your existing Occupational Health and Safety program. By using CSA Z462 as the standard in your facility you reduce incidents in number and severity, and will be compliant with the local laws.

Importance of Hierarchy of Hazard Mitigation

2016-01-19T10:00:00-04:00

There is a hierarchy of hazard mitigation that many people in the electrical industry don't think about, either because of perceived cost, or complexity, or simply not knowing.

A hazard will always be a risk to the worker until it has been eliminated, and this is the goal in a perfect world. Design products and systems that remove the hazard completely.

However, we aren't there yet, so there is an industry standard to the way we look at a risk assessment, whether it is for electrical hazards, or any other hazard in the work place, and we lower the risk to the worker to an acceptable manner.

They are, in order of importance:

Elimination
Substitution
Engineering
Warnings
Administration
PPE

How they are used

When looking at a specific work task, the first thing that should be looked at is, can the hazard be eliminated completely or is there another way to do this that will eliminate the hazard. That covers the first two. Next, is there an engineering change such as a change in the breaker settings, or adding a barrier that will lower the risk to acceptable manner. These first three are where the best system can be developed, these are all permanent changes that require no human interaction after the fact. No continous training, no forms, etc. however the next 3, have only the advantage of lowering the risk, but all the problems associated being prone to human error.

Warnings and Administrative controls include signs, training, best practices, etc. These mitigation techniques require document retention, continous training, and auditing to ensure that the controls are being used. Finally PPE, where too many start, is the last line of defense. If none of the above controls have reduced the risk below the acceptable threshold, PPE is used to ensure that the task is survivable if something doesn't work as planned. For electrical work, PPE is required (not optional) for all energized work over 50V. Shock hazard is the most prevalent and the majority of the systems in the older plants in North America will be over 50V, however not all will have enough energy to be a high arc flash risk.

PPE is at the bottom

PPE is at the bottom, because its goal is to ensure that if there is an incident that it will be survivable by the workers. This doesn't mean that they will be able to go to work tomorrow, it only means that they will live. Arc flash protection is designed to limit thermal energy to the body such that only second degree burns are a result of the incident energy, and that is at 18inches. 18inches is the typical working distance to your torso, meaning that your hands, if they are the cause of the incident, may have greater than second degree. You may not be able to work again, but you will survive all be it a new person.

PPE is very personal to the individual, and it will be the only thing protecting you from an incident. It is also ineffective in lowering the chance that an incident will happen, all of the previous 5 do this either by changing the configuration of the system, or by better training. I have even heard arguments that PPE INCREASE the likely hood of a occurrence. Risk is an equation including the probability of an event occurring and the magnitude of the damage that would result. If you increase the likelihood of occurrence, you INCREASE the risk. PPE lowers the risk by lowing the magnitude of damage (death to life).

In future articles I will talk about each of the hierarchy of controls mentioned here, and provide examples that you can use at your workplace, specifically targeted at Arc Flash Mitigation techniques.

What is Electricity?

2015-08-26T10:00:00-03:00

What is Electricity?

Electricity is everywhere: it powers our homes, our transportation, and our entertainment. Electricity is the reason that you can read this article right now!

But what is electricity?

The importance of understanding the basics of electricity (what it is and how it works) cannot be understated. Without understanding electricity, you could not design all of the electrical marvels of technology we have today (from the modern power grid to a cell phone). Even more importantly, you wouldn't be able to protect yourself from electricity. So in order to understand how electricity works, I'm going to first talk about the two key components that make up electricity: voltage and electric current.

Voltage

Voltage is the difference in electric potential energy between two points. If you pick a single point on an electrical circuit and ask “How much voltage is here?” the person trying to answer you will probably say “compared to what?” Think of it kind of like distance. If you're standing at one end of a room and I ask you “How much distance is there?” you're going to be confused. If I ask you “How much distance is there between you and the other side of the room?” you're going to tell me that there's roughly 20 feet between you and the wall.

Voltage works the same way. If you look at two points in a circuit with stuff between them, you can use a multimeter to figure out the voltage.

Electric Current

Current, on the other hand, is harder to explain. Everything in the universe is made up of atoms: the building blocks of life. Atoms have three parts: protons, neutrons, and electrons. Protons and neutrons hang out together and form a sort of “core” of the atom, while electrons float around outside this core. In an electric circuit, one electron gets bumped off its atom and moves to a new atom. The new atom doesn't want too many electrons (it had enough before!) so it kicks off another electron. This happens over and over again millions of times in a circuit, (One amp means roughly 6.24*10¹⁸ electrons are going around the circuit every second!)

Electrons moving creates electric current, and electrons only move when there is an electric potential energy difference (voltage) between two points. The electrons are moving to try and bring balance to the system (bring the voltage between two points to zero).

Rho is resistivity, a physical constant that changes based on what material the electrons are travelling in. L is the distance the electrons have to travel, and A is the cross sectional area of the medium they're travelling in. Resistance depends on the mathematical equation shown above. So a really long, thin wire would have a much bigger resistance than a shorter, thicker wire.

Think of electricity like water in a pipe. It's easier to move water a short distance through a big pipe than it is to move it a long distance through a skinny pipe.

The Danger

This is where electric current gets very dangerous. Your skin is a great insulator, which means that it has a really high resistance. But the human body itself is a great conductor, which means it has a low resistance. Think about thunderstorms: why is it always safer to be away from the water? Especially salt water? Salt water is a great electric conductor. To electricity, the human body looks like a big bag of salt water: if you can get past the plastic (insulator), you can zip through the water (conductor) to the other side with ease.

When the current moves through your body, it can do a number of things. The heat from all those moving electrons can cause serious internal or external burns. Even worse, the electric current coming into you can interrupt the electric current that keeps your heart pumping!

So how can we keep ourselves safe?

People haven't been sitting on their haunches for the last 200 years since electricity was discovered. The most common ways of protecting people from electricity involve proper grounding and insulation design, appropriate personal protective equipment, and safe working practices. We've come up with things like equipotential zones and isolation transformers that greatly reduce the risk involved with working on or around electric equipment.

These are just a small sample of ways that we stay electrically safe today. What could you do to keep yourself and your designs electrically safe?

6 Reasons to Have an Electrical Safety Program

2015-08-19T10:00:00-03:00

When I first started researching and writing about electrical safety, I didn't really know what an electrical safety program was or why someone would need it. I had a gut feeling that if you were someone working with electricity, an electrical safety program would keep you safe. I felt like that was enough. However, all safety programs help keep workers safe, so why would a business specifically want an electrical safety program?

According to the ESFI, between 2003 and 2010 there were 1,635 workplace fatalities related to electricity in the private industry. Between 2003 and 2010 there were also 20,150 nonfatal electrical injuries involving days away from work in the private industry. Although the number of accidents related to electricity has been dropping steadily every year, the fact is that one accident is one too many. It is very important for your workplace to have an electrical safety program to help lower the risk when working around energized equipment, so here are 6 great reasons why you can benefit from an electrical safety program:

1 Employees will be well educated.

An electrical safety program will ensure that employees are well informed and have up-to-date training for their jobs. The two major causes of electrical accident fatalities are contact with overhead power lines and contact with wiring, transformers, and other electrical components. Well trained, well informed workers will cause fewer accidents and be less at risk.

2 Fewer accidents means money saved.

Statistics gathered by the NFPA show that the average electrical accident costs $80,023. This cost includes both workers' compensation (medical bills and wages while unable to work) as well as equipment costs.

3 It can increase productivity by causing you to schedule your work better.

Accidents are time consuming. Before you work on it, equipment should always be de-energized when possible. Having a procedure in place for scheduling this type of work ensures that work on one system is not impacting the operation of another electrical system. This leads to greater uptime for your facility.

4 It makes it easier to adapt to changing safety standards.

When you're on the bleeding edge of safety progress, it will be easier for you to adapt to changes to any standards you currently follow. When it comes to safety, you want to lead from the front, not follow behind.

5 Having an accident free workplace builds trust.

This might be one of the most important points. You won't have unexpected shut-downs and won't be incurring high accident costs. Your leading stance on safety puts you ahead of the competition. People will want to work with you, for you, and will want to invest in you because being accident-free makes you reliable.

6 It's very easy and simple to do!

There is a wealth of tools and information available to you when creating your electrical safety program, and they're easy to combine with whatever current safety program you might have in place. IEEE, NFPA 70E, and CSA Z462 can help get you started, but there's all kinds of information out there on the internet if you take the time to look.

And those are 6 great reasons why an electrical safety program can benefit you. Thanks for reading!

Is a Change Management Process Important?

2015-08-13T10:00:00-03:00

First, what is change management or a change management process?

A change management process is a set of steps, or workflows, that document a change from proposal - approval - implementation - testing, allowing for each step to be verified and tracked.

Practically it is a process that includes the document control system, procurement, management and engineering; allowing for all parties to be informed in the decision making process. A good change management process allows for different business units within a facility to work together effectively and allows everyone to have their projects completed in an effective manner.

What about the Power System

The electrical power system presents a unique challenge to any change management process. Today it is easy to change a setting in a protection relay or electronic overload without leaving your desk, but this can cause selective coordination issues.

Another challenge is the relative ease to change breakers, cables, add loads, change loads, etc compared to other systems within a plant, and the affect that these changes can have on the over all system. For example, adding a large motor to a spare bucket in a MCC lineup is relatively simple, and typically the only item that will be looked at is the loading on the MCC. If the commissioning of the motor doesn't trip the upstream protection you are good to go.

Well that is the thought: in reality you have very likely affected the system load flow by adding additional inductive load. You've also possibly changed the incident energy levels at the MCC buckets leading to improper PPE during energized work.

A change management process will include the following:

Propose the change to the engineering group
Engineering will then study the affects by updating the power system studies
Implementation documents are created, and existing document revised (and tracked)
Installation is completed and any field changes reflected in the documents.
Engineering verifies completed installation and updates power system model

Implementing a Change Management Process

Most facilities will have a process for large projects - whether they are maintenance projects, or capital improvements - these projects will have their own process that will likely capture all the steps that we previously mentioned. However, it is the smaller projects that can get lost in the mix, and add up to significant changes to the power system during the 5 year study cycle. Both CSA Z462 and NFPA 70E recommend that the arc flash analysis be updated every 5 years, which will include updating all the other power system studies.

If the power system model, or at a minimum the drawings that the model is based on, are continuously updated, the process of updating the arc flash analysis will be trivial.

For smaller facilities I always recommend that they have a single, well developed and controlled set of one-line diagrams that they use to document all changes to the power system. This can be a hard-copy that the electrician red-lines as they go, and in a lot of cases this is preferable. When the drawing has been redlined enough, or on a set schedule the CAD version will be updated and a new revision issued. This system has the advantage of the drawings being with the person that is completing the work, and being current.

If the facility is larger, or has the staff to accommodate it, an electronic process can be implemented where the changes are proposed, reviewed, accepted, work orders created and work verified.

Conclusion

Change management is essential for a plant, faclity or process to operate smoothly and predictably. Easypower has a dedicated package called Electrical Change Control Module (ECCM) which tries to solve these problems by introducing a workflow that enables everyone to get their work done. Below is a webinar they published in Dec 2014.

https://www.youtube.com/watch?v=a_fJPEumoGw

If you have had an opportunity to use ECCM at your facility I would like to hear your thoughts about it!

Electrical Safety Program Wrap Up: Documentation, Evaluation and Corrective Action

2015-08-11T10:00:00-03:00

Now that you've finished with Implementation, you electrical safety program is almost complete. The only things left to do are to figure out how to keep track of your electrical safety program, and how to improve it.

You can do this with Documentation, Evaluation, and Corrective Action.

Documentation

Unlike our article on Document Housekeeping, Documentation is a section of your electrical safety program that outlines how you'll be recording everything. You'll need to sort out how it is that you will be documenting your safety program. This includes training manuals, energy study reports, safety meetings, and accident reports.. You'll also want to define who is responsible for keeping this documentation up to date, and you'll want to figure out the optimal documentation format to make sure that everyone is compliant with the electrical safety program.

Evaluation and Corrective Action

Finally, you need a section for Evaluation and Corrective Action of your electrical safety program. At a minimum, electrical safety programs should be reviewed annually, but this timeline can be customized based on your business.

You need to define how you're going to measure the success of your electrical safety program so that you can come up with a plan to correct any problem areas. Processes like safety audits and accident investigations (including who is responsible for each) can go here.

The best electrical safety programs are not designed perfectly on their first attempt, iteration is key to keeping your work environment safe.

Closing

Above all, know that this guide is simply a brief overview to help get you started on the right path, and is not even close to an exhaustive list of procedures for creating your electrical safety program. Always consult your national and local electrical safety standards, as well as any extra guides that delve into more detail on the specifics of how you should go about pursuing each of the topics listed above. A great starting resource is “Electrical Safety Handbook, fourth edition”, by Cadick, Capelli-Schellpfeffer, Neitzel, and Winfeld.

How to best use the Power System Study Report

2015-08-06T10:00:00-03:00

If you have gone through the process of completing the power system study report, or have had an outside consultant provide you a binder with all the deliverables, now the real work begins. Having a power system study completed is not the end: it is the start. The reasons to have a power system study report completed in the first place can vary from getting incident energy values for PPE selection, to future plant expansions.

In this article we will outline some of the more common uses of a complete power system study report. We'll also include suggestions about how to approach the recommendations that were included.

Short Circuit Study

Let's start at the beginning with the short circuit study. The first thing we will look at is the type of recommendations that you will be expecting to receive in the report. First there is going to be any equipment that is not rated for the existing short circuit current that is available within the facility. There are a couple of reasons for this to happen: the first is that the equipment was purchased undersized, however the more likely scenario is that there have been system changes. These changes could be either at the utility level - adding additional transmission capacity - or within the facility itself.

Typically the best way to fix these issues is to replace the equipment.

Another output of the short circuit study will be areas that are marginal. This could mean that a change in the system could exceed the fault rating on the affected equipment. For these, investigate the switching scenario that was used, and figure out if there are any additions to the plant planned in the future. A decision will then be made to determine if the equipment should be replaced now, or flagged as an area of concern when there are system configuration changes in the future.

Protection Coordination Study

The protection coordination study will likely include recommendations for areas that are mis-coordinated. With the help of your consultant you can go through the areas of concern and develop a list of what needs to be changed. With proper selective coordination, the system will operate in a predictable manner in the event of a fault or overload.

In a lot of cases it will be easy to change the settings on the relay, or LSI(G) breaker, to solve the coordination problem. If the settings can't be changed with the existing equipment, the protection device will need to be replaced. If the mis-coordination is something that will not affect a large portion of the system, or is the same circuit (a primary fuse and secondary breaker on a transformer) the decision may be to leave the mis-coordination as it is.

Another consideration of selective coordination is the incident energy in the case of an arc flash event. Clearing the fault as quickly as possible will limit the heat energy available, and will reduce the arc flash boundary and PPE required for energized work. These decisions will be simplfied when going through the electrical safety program.

Incident Energy Study

The incident energy study is a critical input to the arc flash analysis, which is a critical portion of the electrical safety program. If you haven't developed an electrical safety program or an arc flash risk analysis, a great way to start one is with an incident energy study in hand. With the incident energy known at all the equipment, you will know the arc flash boundary and can start developing PPE levels for energized work.

Arc Flash Risk Analysis

The first step is to develop a risk assessment as associated with the arc flash hazard. Within the company develop a list of the various tasks that will expose workers to an arc flash hazard. From there you can determine what incident energy is considered too high of a risk for energized work, and cross-reference with the incident energy report. You can implement mitigation techniques for any areas that have a high incident energy.

Incident Energy Mitigation Techniques

There are only two methods to lower the incident energy at a bus: one is to lower the time the arc is present before being cleared, and the other is to lower the magnitude of the current. To shorten the time that the arc is present, modifying the protection settings will work well. Sometimes this may mean sacrificing selective coordination, which is a compromise that can be made on a case by case basis.

It is harder to lower the available current. You can add impedance - add inductance or more cable - which is typically not practical, or break up the large motors onto different buses to lessen the back feed current during a fault. Neither of these are very practical, and are typically ignored.

Load Flow Study

Finally the load flow study is the place that you can really start to save money. Using the results of the load flow study report, you can see where in the system you may have opportunity to increase efficiency. We've already written about who can leverage a power system study :engineers aren't the only group that can use the load flow study in their everyday work. A couple of examples are how capital projects (power factor correction) and operations (load scheduling) can help your facility save money and pay back the cost of having a study completed in the first place.

Power Factor Correction

By ensuring that the power factor is matched as close to 1 as possible, you system will be operating with the least kW, meaning that you will be paying for the least amount of energy from the utility. The load flow study will determine the best place to install power factor correction capacitors, whether they should be staged or always online.

Load Scheduling

If your facility has a large energy draw, and a lot of motor load, then your power bill will likely be in multiple parts. Each part will have different charges. For example:

Energy -kWh
Max Demand - kW with a rolling average
Power Factor - too much kVAR draw

The load flow study allows you to figure out your baseline operations. You can then start making changes to how new loads are added, and determine the most cost effective way to operate the facility without hurting production.

Conclusion

There are a lot of useful projects that will optimize the operation of your facility: we have only scratched the surface with this article. If you liked this article, feel free to share it. If you let us know, we'll add more articles like this one, about utilizing a power system study at your facility to give your business a competitive edge.

Electrical Safety Program: Training and Clear Communication

2015-08-04T10:00:00-03:00

This article is going to talk about putting your plan into action.

The next section to include in your own electrical safety program is Implementation. As they saying goes, you've planned your work and now you have to work your plan. This involves checking all of your available resources (electrical system data, personnel, equipment, cash, etc.) and getting to work at making your working area safe. This phase should outline any precautions and preventative measures that need to be taken, such as setting up warning signs and labels, and making sure all equipment meets the safety regulations defined in the planning phase. You'll also want to make sure you have enough personal protective equipment and insulated tools and have a way to obtain them and a method for approving them. PPE should be examined before each use and should be replaced if there are any abnormalities or damage to the PPE.

Training

The implementation phase is also where you'll outline your electrical safety program's training plan and schedule. Training methods are varied and can include a healthy mix of classroom and on the job training. Job specific training should be mandatory before performing any new job. If the job is performed infrequently, you should establish a set period of time that can pass before it becomes necessary for an employee to repeat the training for that particular job. Something to stress here is diligence: complacency with work can be just much of a hazard as anything else. Everyone should always be up to date on their training for any job.

Job Planning

Speaking of jobs, you'll also want to outline processes for job planning meetings. These should take place before a job dealing with energized equipment begins. You need to determine who should hold the meetings, identify the hazards involved with the job, perform a risk assessment, develop a plan for actually performing the job, and identify any PPE or tools required to complete the job. An example can be found in CSA Z462.

The Importance of Communication

You'll also want your electrical safety program to stress the importance of clear communication and awareness here. If an employee doesn't understand something related to the work they are going to be doing, they should be encouraged to ask questions. Any questions should only be answered by qualified individuals who are sure that they know the answer. A good rule of thumb is that if you don't know something, confess to not knowing and find someone who does. Never give a false or incomplete answer. Likewise, if a job is going to be performed around heavy equipment, make sure the communication protocols are clearly defined so that people don't misinterpret information: confusion will lead to human error. And please, try to avoid jargon. You can find our article about the evils of jargon in the workplace here.

Finally, your electrical safety program will need to explain your emergency prevention and response system for when things eventually do go wrong. All employees should have some basic form of emergency training, but job specific emergency responses (such as responses for accidents around high voltage equipment) should be outlined.

Now that you've got an idea of how to implement your electrical safety plan, you'll want to start thinking about Documentation Methods, Evaluation and Corrective Action.

What is a Load Flow Study

2015-07-30T10:00:00-03:00

A load flow study is the trickiest of the critical four power system studies: it evaluates your power system's capability to adequately supply the connected load while staying within proper voltage and current ranges. The load flow study report will determine the voltages and power factor at all your buses, as well as currents or power flow on all your feeders. A load flow study is also called a power flow study.

Why have a load flow study completed?

Completing a load flow study on an existing system will provide recommendations for system operation and optimize the system operation to minimum operational costs. Understanding the power flows on various system feeders will allow the operators to understand if there is spare capacity, if there are areas of the plant that are overloaded, and if there are operational configurations that will save energy and the associated costs.

Energy Savings

There are a few results of the load flow study that will help you understand if the power system is operating in the most efficient manner. With the rising cost of energy, it makes sense to ensure that the power system is operating in the most efficient manner for as many different configurations as possible.

One way to do this is to add power factor correction to the system that will limit the system's energy consumption. With the load flow study you will be able to understand where a single bank of power factor correction capacitors will make the best difference.

A larger energy cost saving measure is removing new peak demand from the system. A load flow study will allow operations to understand the best way to limit the impact of a new demand peak.

Capital Expansion or Contraction

The one sure thing about an operating facility is change. Whether there are plans for expansion or system contraction, it makes sense to have a load flow study available to help understand which feeders have spare capacity. If system contraction is needed, a load flow study will allow the engineers to determine which feeders can be used to consolidate the remaining load.

Consolidating existing equipment loads to a couple of larger transformers will allow the transformers to operate near their optimal efficiency. This will also allow very lightly loaded transformers to be removed from the system, removing the magnetization current that is wasted energy.

When to have a load flow study completed?

The information that is critical from a proper load flow is the voltages and power factor at all your buses, and currents or power flow on all your feeders. With this information you will be able to make important decisions on where to add or remove load, and where power factor correction can be added to increase the efficiency of your system.

How to get one completed?

As with other power system studies, the hybrid model as outlined in Getting a Power System Study Completed is the preferred method to get a Load Flow Study completed at your facility. Understanding how the facility operates is critical to creating an accurate load flow model.

We suggest to start with the most common system configuration that has meter and motor information. When the model is developed, and matches the system configuration, then the model can be built upon for the less used switch configurations.

Electrical Safety Program: Planning Risk Assessment - What Makes an Electrically Safe Working Condition?

2015-07-28T10:00:00-03:00

In our previous article, we got started with the Planning section of your electrical safety program, which included legal standards and hazard identification. This article will cover the planning portion for risk assessments.

Probably the most critical part of the planning section is to define what makes for an “ Electrically Safe Work Condition ”. Your electrical safety program should explain procedures for de-energizing equipment here. This section should also outline safe working distances from currently energized equipment including transmission lines, as well as safe practices for testing to see if equipment is still energized or can be confirmed to be de-energized. In order to determine whether a working condition is truly electrically safe, your electrical safety program needs to explain how to perform a risk assessment.

Risk and Risk Assessment

First, let's talk a little bit about risks.

A risk is the chance that a hazard could be unmanageable and therefore cause harm to personnel or equipment. For example: energized equipment on the job site is a hazard, but working on energized equipment is a risk. A good electrical safety program identifies all of the potential hazards on the job site and assesses the risks involved with working on or near the hazards.

Once a hazard has been identified, your electrical safety program needs to outline a risk assessment procedure. Assessing a risk involves determining the possible injury to a worker, and weighing that against the likelihood of the injury actually happening. Here's a fairly basic example:

An employee is required to work on a piece of equipment. That equipment is energized, and the risk associated with the hazard of working with energized equipment is fatal shock with a fairly high chance of occurring. If you de-energize the equipment, the shock hazard has been removed, lowering the risk associated with the task, and the equipment can be deemed safe to work on.

If the equipment could not be de-energized for whatever reason - such as testing electrical circuits - a worker can reduce risk by wearing the appropriate personal protective equipment (PPE). Unless absolutely necessary equipment should be always be de-energized before work is performed.

Your program should clearly explain who is qualified to assess risks and should cover any training a person might need to become qualified to assess risks. Ideally, all employees and employers should be trained and qualified to identify hazards and assess risks. A more thorough explanation of hazard identification and risk assessment can be found in Annex F of CSA Z462-15.

Next, you'll want to get started with implementing your electrical safety plan.

Protection Coordination Study

2015-07-23T10:00:00-03:00

In power system studies - the critical four I said:

The purpose of the protection coordination study is to verify that the various protection devices in your system, relays, breakers, fuses, etc. are coordinated correctly and are sized appropriately for the equipment that they are protecting.

which is very true. To expand on that, a protection coordination study really has two purposes. First it ensures that the electrical equipment is properly protected from over-currents and overloads. Secondly the study determines that the selective coordination is employed such that the system reacts as intended and in a predicable manner. You should (almost) always sacrifice equipment protection for selective coordination. The cases where the opposite is true is a topic for a future article.

[caption id="attachment_1300" align="aligncenter" width="676"] TCC from an ETAP example file[/caption]

A protection coordination study will consist of time-current curves (TCC) of all the electrical equipment, protective devices and large motors. Above is a sample TCC showing a circuit for a 50hp motor, it shows the breaker (CB16) that protects the motor from over-currents, the over-load protection (OL_H1), and the fuse (Fuse3) that feeds the MCC. The dashed line at the far left shows the motor starting and running curve, the next shaded area is CB16 and OL_H1. ETAP models them as a system and only shows the parts of the curves that are relevant. At the far right is the fuse.

There is no overlap between the motor curve and the motor protection (CB16 and OL_H1) so therefore the motor will operate as intended, and there is no overlap between the feeder fuse and the motor protection, so if there is a fault on the motor circuit the main fuse won't activate. If there was an overlap, then there is a chance of the fuse operating on a motor fault, removing a larger portion of the system from service, and possibly making it difficult to troubleshoot the issue to get the system back into operation.

Why do I need a protection coordination study?

You will need a current protection coordination study at your facility to ensure that your system reacts to a fault in a predictable manner and to know how long a fault will be present before the protection takes action. This time is critical information for an incident energy study, and will greatly affect the severity of an arc fault.

When should a protection coordination study be completed?

A protection coordination study will be completed during the design phase of any facility, however after that it will be reviewed on a periodic basis, but at least every 5 years. As with all power system studies, if there have been changes within the system, you should verify that the protection is still adequate.

Another time to revisit the protection coordination study is when equipment is experiencing nuisance tripping: this can be caused by abnormal currents in the equipment, or a faulty relay.

How do I get one done?

I always recommend that the protection coordination study be completed with software, unlike the short circuit study. It is extremely hard to print curves to scale for overlaying, and to try multiple options when an issue presents itself. However, it is relatively easy to add different devices to the circuit and verify protection and selective coordination when using power system modelling software like ETAP, SKM Powertools or Easypower.
To determine the best way to get a protection coordination study completed check out this post from a couple of weeks ago. In it I explain the various methods that you can use to complete a power system study, which can work for any individual study.
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Electrical Safety Program: Planning Standards and Hazard Identification

2015-07-21T10:00:00-03:00

So you've gathered your data and finished up with the housekeeping portion of your electrical safety program, and you've now also gotten your program's roles and responsibilities clearly defined. The big question now is: what comes next?

Planning

The next thing you need to include in your electrical safety program is the Planning section. Here you should outline all the safety codes, regulations, and standards that your electrical safety program adheres to. You want to make sure that your electrical safety program is, from a legal point of view, bulletproof. The odds are high that you will need to adhere to one of CSA Z462 (if you're in Canada), NFPA 70E (if you're in the United States), or EN 50110 (if you're just about anywhere in Europe). Broader organizations that produce standards include OSHA, IEC, IEEE, and ANSI. This is in addition to any standards specific to your location, including provincial and state regulations.

Your planning phase also needs to have some occupational health and safety objectives and targets. Consider the types of things you want to prevent, including things like physical harm to workers and damage to equipment. In essence, the question you're trying to answer here is “What is my electrical safety plan going to do to keep people safe, and what kind of safety goals does it have?”

To expand on this, an important part of the planning phase is Hazard Identification and Risk Assessment. These topics go hand in hand, so we'll get you started on Hazard Identification, and will cover Risk Assessment in a later article.

Hazard Identification

A hazard can be considered to be anything at work (an item, a condition, an action, etc.) with an unacceptably high potential to cause either bodily harm to persons on the job, or damage to equipment. Your electrical safety program should clearly outline how to identify a hazard. One example would be a procedure that must be followed to safely determine whether or not equipment is energized. Your program should also indicate who is qualified to identify hazards before work is to be attempted, and should cover any training a person might need to become qualified to identify these hazards.

Now that we have hazards out of the way, the next thing we want to talk about is Risk.

Electrical Safety Program: Health and Safety, Your Roles and Responsibilities

2015-07-14T10:00:00-03:00

Now that we've gotten all of the data gathered on your current working situation, and we've finished with all the preliminaries, we can get started with the General Occupational Health and Safety section of your electrical safety program!

Your General OHS should reiterate the purpose of your electrical safety program. It should begin with a general explanation of what your electrical safety program is intended for. Feel free to re-state the Scope here. You can then talk about Roles and Responsibilities.

Roles and Responsibilities

The roles and responsibilities sub-section explains who is responsible for establishing, maintaining, and reviewing the electrical safety program, and outlines the process by which the electrical safety program is measured and monitored. For now we will assume that this person is you. The team creating the electrical safety program should be a healthy mix of corporate management and ground level employees, as well as safety officials. You want to be able to cover as many scenarios as possible, and a large team with a broad range of different experiences can help accomplish that goal.

This section will outline how affected workers are involved in the development and implementation of the program. Sometimes very important aspects of an electrical system can be overlooked by someone who is not intimately familiar with the finer details and inner workings of the electrical system. If you know someone with more technical or practical experience than you or your team have, it is always a good idea to consult them before implementing a new safety program.

Another thing that roles and responsibilities needs to explain is the role of managerial and executive staff in the creation of the electrical safety program. It is very important that management be made aware of the risks involved in working with any energized equipment at your workplace so that they can make informed decisions about any jobs taking place.

Next, roles and responsibilities should make it abundantly clear that all persons involved in the operation of the facility should have the self-discipline to follow the electrical safety program.

The roles and responsibilities should clearly outline who is and who is not qualified to work a specific job. A qualified worker is someone who has sufficient up-to-date training in the particular job, understands the risks involved and knows how to best protect themselves.

After getting the general OHS completed, you're ready to take the plunge into one of the really big sections of your electrical safety plan: the Planning section, coming next week!

Your Electrical Safety Program: Document Housekeeping

2015-07-07T10:00:00-03:00

Once you have all of the necessary data in one spot for the electrical safety program, you will have to start organizing the binder, or electronic file for the document itself. Let's start with the document housekeeping, this will give you a visual checklist of all the sections that need to be addressed.

The first tasks that need to be covered are what I call the “general housekeeping” portions of the document. In order, these include the Table of Contents and List of Figures, the Scope, Reference Publications, and Definitions.

Table of Contents and List of Figures

The Table of Contents and List of Figures are easy: they're a list at the beginning of your program that lists all of the main items and where to find them. These will usually be created last even though they're the first thing a reader will see. You can look to any book, text, or standard for examples of the Table of Contents and List of Figures. These are important so that you can quickly find any information in your electrical safety program.

Use this section of the document to list out the sections, tables, etc that you want to include in the electrical safety program.

Scope and Reference Publications

Next, let's talk about the Scope for your electrical safety program.

The scope should include some general information about your program including; what kind of business or facility the program is for and what kinds of accidents the program is trying to prevent. It should state where the electrical safety program can be applied, who is responsible for following the electrical safety program, and what situations the electrical safety program can be used for. It can also include what measurement units are used (as a Canadian I prefer SI units). Any terminology that could be confusing (due to words having multiple meanings) can also be described here.

Reference Publications include any material you may have used when designing your electrical safety program - including SparkyResource. This section describes the sources of information including internal documents, national and international standards, technical papers, etc.

Definitions

Definitions are the big brother to the terminology section in the scope. The definitions section of your safety program serves to clearly explain any words that might not be familiar to new employees, or even to veteran employees who have new responsibilities and have limited experience with a particular topic.

The definitions section helps avoid confusing jargon by defining the exact meanings of words as related to the electrical safety program. Check out our article on the misuse of jargon before you go on to the next section, Jeff explains the importance of having definitions for the commonly used terms in your workplace.

As far as the less exciting (but still important) stuff is concerned, that's it! Next week, we'll get started with the real meat and potatoes of your electrical safety program: The General Occupational Health and Safety System.

Electrical Safety Program: Getting Started

2015-06-30T10:00:00-03:00

If you're reading this, you must be interested in starting your own electrical safety program for your company. Electrical safety is important.

Before we dive into the nitty-gritty of procedure and policy though, we've got to take care of a couple of things. Before you get started designing your electrical safety program, you need as much information about your job areas as you can get.

Electrical Safety Brainstorming

Here's a good list of items you may want to consider when building your electrical safety program:

What are the electrical hazards in your workplace? Consider things like uninsulated metal tools near energized equipment.
What jobs require work on energized equipment? An example could be testing circuits to determine that they are working correctly.
Who performs the work on energized equipment? Only someone qualified through appropriate training.
How do you currently reduce risk of harm to personnel and equipment? Some ways include wearing protective clothing and establishing safe working distances from energized equipment.
If you already have a safety program, is it adequate? How long has it been since it has been reviewed?
How long has it been since the last incident energy study has been done on your workplace? Should your studies be updated?
Who needs to be trained to work at your facility and what kind of training do they need? Ideally, everyone should have basic electrical safety training as well as job specific training.
What kind of PPE is required for which types of jobs? Some basic repairs on non-critical equipment might only require insulated tools and insulated gloves, while working near an arc flash hazard might require an arc-protection suit.

Electrical Safety Program Purpose

Your electrical safety program should be able to answer all of these questions.

Asking these questions before you begin creating your new electrical safety program will help you figure out which current safety practices you can keep. These questions also help to highlight problem areas that need to be looked at, giving you a good idea of what you should focus on changing.

You aren't limited to these questions - you should also look at anything specific to your workplace that isn't listed above.

For the next set of sections you'll need when putting together an electrical safety program, check out our article next week on Documentation Housekeeping.

How to Create an Electrical Safety Program

2015-06-23T10:00:00-03:00

Electricity is a powerful and dangerous tool used by people all over the world. It is very important for your workplace to have an electrical safety program to help lower the risk when working around energized equipment.

A good electrical safety program is much more than a list of rules to follow. A good electrical safety program will minimize the risks involved with working on energized equipment. This includes reducing risks of injury to personnel, such as you and your colleagues. It also helps reduce the risk of breaking equipment when it needs to be used or maintained, saving you valuable time and money! Something so valuable should be a monumental task, right?

Below, I've laid down a list of steps that you can include when building your own Electrical Safety Program, tailored to the specific needs of your facility or business. These steps have been grouped into “sections” that most safety program documents should have.

This list is not exhaustive, there is always be more that you can do to keep your workplace safe. This is a simple guide to get you started. If you think of something important that hasn't been mentioned in this series let us know!

Jargon a talking killer - Clarity in Communication

2015-05-28T06:00:00-03:00

I was reminded of a presentation [1] by Al Winfield at ESW 2015 in February after reading point 5 "Replace jargon with clarity." of the hit post 10 top writing tips and the psychology behind them.

Listening to Mr. Winfield I immediately thought about the jargon that is used at the job site, or the office, every day. A great example is "throw the switch", how does someone throw a switch that can weigh hundreds of pounds? When I listened to Al's presentation and then re-read his paper, two items really intrigued me regarding jargon and electrical safety:

If the listener (or reader) doesn't decode the message of the speaker (or writer) no communication has taken place.
You can't throw a switch

Clear Communication

When you are at a tailboard or job box (jargon for pre-job meeting) you must be clear in how you present the details of the job, if the audience doesn't glean the same meaning as you intend no communication has taken place. Don't use words like:

prior to
at the end of the day
as we speak
etc

Instead use words that are simple and concise like:

before
the objective is
now
etc

Be clear with the job objective, and precise in the communication of the tasks/hazards/etc.

Jargon and Electrical Safety

Every industry has jargon, and those that thrive in it. We use jargon for two reasons, to make others feel stupid and make ourselves feel smart.

Why you use jargon. You think jargon makes you sound sophisticated. Or you're hiding the fact that you don't actually understand what you're saying. - Without Bullshit

Understanding that most of the people you talk with have a 7th grade reading comprehension level, so you should always try to use words that a 7th grader could understand unless there is no substitute.

Using clear language allows listeners to grasp your meaning instantaneously.

Next time you need to throw a breaker make sure you communicate that you really want to open (or close) the breaker, and be sure that everyone around you knows exactly what is going to happen.

[1]	The paper - Good Communications - The Essence of Safety

Data Requirements for Power System Studies

2015-04-03T06:29:00-03:00

Now that we have an understanding about the importance of good data collection for power system studies, and how to prepare a plan for data gathering, now we need to understand exactly what is needed for each power system study type and specific pieces of equipment. However, there is some information that is needed no matter what study is being completed.

What do they all need?

Utility information
Nominal system voltage levels
System configuration with the following equipment:
- Transformers (with impednance, voltage and configuration),
- Configuration switches and circuit breakers
- Switchgear, mccs, switchboards, etc down to the voltage level you are interested in
Any large motors and other generation on the site.

With this minimal information you can prepare an adequate short circuit study that will give you values for the short circuit on any of the buses above. These will be very much worse case as we haven't gathered any additional impedance information. This study would be useful for design and specification purposes when you are purchasing equipment for a new facility.

Short Circuit

What information needs to be added to get a decent short circuit, well it is everything above and the following:

Distribution equipment short circuit withstand and full load information
Transformer ratings
Protection equipment manufacturer information, complete with full load rating and short circuit withstand ratings.
Cables connecting distribution equipment, complete with size, type, configuration and length
Lumped motor and non-motor loads at all distribution equipment

With this information you will be able to determine the worse case fault scenarios based on your system configuration and determine if there is any equipment that hasn't been designed to withstand that level. If there is, this is the first thing that must be addressed in your facility.

Protection System

The additional information that is required for your protection system includes everything that is needed to determine how your protection is going to activate in the event of a fault as determined by the short circuit study.

For this you will need to determine the following:

Trip characteristics of all relays
Tripping times for all breakers
Complete manufacturer information for the fuses in your system
Manufacturer information for all moulded case breakers
Any large motors, and their protection broken out. This is to ensure that the protection is coordinated with the worse case starting current.
For large motors the interial load, and starting times may be required, along with any design type information.

With this information in the model, time current curves, commonly called TCCs can be developed and reviewed to determine if the system will operate in the event of a fault as intended. If there are any overlapping areas that may be cause for concern, this is where they should be addressed. If there is a fault, predictability in how it will be cleared is very important in the aftermath. If multiple protection devices activate it is much harder to determine the cause if there isn't much visable damage.

Incident Energy

Getting into the meat and potatoes of the studies. As I mentioned in the previous episode, incident energy, and the resultant arc flash risk analysis, is the single most cited reason when I ask why the prospective client is interested in getting a study completed. This is where a lot of time and care needs to go into gathering the data necessary for the study, and where the previously stated numbers related to time come into play.

Along with all the information that was gathered for the barebones short circuit and protection coordination, more detailed informaiotn on the imedances withint the system and loads need to be gathered. All information, for any place that the electrical safety program required a detailed label, based on whether or not there will be energized work, needs to be put together.

What type of loads?

This information amounts to the following, starting at the load. All motors 25hp and above need to be broken out. The actual size whether it is 25hp or 50hp isn't as important as they are broken out. Induction motors contribution fault current for short periods of time, and the magnitude is proportional to the motor size and intertia. This fault current, is not “seen” by the protection relay upstream and doesn't account for how quickly the protection will clear the fault, however it does contribute energy into the incident energy value. However, it is not a linear relationship, therefore a large number of small motors will not contribute the same values as a single large motor, therefore it is important to break out the larger motors, I like to use 25hp as the break point, and then lump the remaining motor load.

How are the loads fed, what is the impedance?

The cable information, including the size, configuration, raceway material and length is needed from the load to the MCC, or distribution panel. This all contributes to the overall impedance of the cable, and affects how much energy that motor can contribute. If the length is hard to determine, walk it down and err on the shorter side. Since this fault current doesn't affect clearing time of the protection, erring on less impedance will give you a worse case incident energy everytime. In a future episode I will discuss why this is important, in short it has to do with the time portion of the incident energy equation.

The motor protection, including overloads and MCP is good to have here, it is not critical, but since you will likely be in the bucket gathering the data, it is better to have it now. It will be important if qualified workers are needed to complete energized work at a local motor disconnect, or within the bucket itself.

If the detailed cable information mentioned for the motor feeds wasn't gathered during the short circuit it is important to get it here.

Load Flows

When you have all this information, the load flow is mostly complete, we need to get into the operational details. We have already mentioned the motors, and breaking them out, now we need to start thinking about the non-motor loads, and just as importantly, what is a good “demand factor” that can be applied to these.

For example, for all the other studies we assume that that motor or load is running at 100% kW, however this is rarely the case. For an accurate load flow, load factor percentages need to be added to determine the loads and then the resultant report can then be checked against any metering information that you may have at your facility to determine that it is accurate.

If this information is hard to come by, a good starting point may be as follows:

Motors greater that 250hp - 100%
Motors 100hp to 250hp - 75%
Motors less than 100hp - 50%
Non-motor load - 75%

From this iterations can be made to get closer to actual values that can be used as a basis of the report.

Conclusions

Now that you know why you may need a power system study at your facility, how to get started with getting the studies completed, and with this series how to gather the data necessary for great reports. The next step is to get started.

If you need assistance send us a email with a brief description of your system and how to get back to you. We look forward to hearing from you.

Plan you Data Collection Effort

2015-04-01T06:27:00-03:00

In the first post of the series we talked about why having good information and data is critical for an accurate power system study. If you haven't read that one yet, stop reading an check out Data Collection for Power System Studies and then head back here. This article will talk about the planning process of getting all this critical information together, and the last post of the series will be cataloging what information is required for specific devices, equipment, etc.

How to get it

The data required as outline is a lot to swallow in one go, however at your facility and elsewhere most of this information is can likely be found on existing drawings, cable schedules, operations/maintenance manuals, lockout tagout procedures, maintenance databases, relay testing reports, etc. the first step after knowing what is needed, is to start brainstorming where this information can be found already, and then verifying the accuracy of this information.

Use existing information

Existing data from old reports, single line diagrams

Have a central location/database to put all the information

It is important to have a central location for all this data, a equipment database, or spreadsheets all work. If you are completing the study in house, adding the information directly in the model is another great way. ETAP and other modeling software have methods to track the validity of the equipment information, or you can circle and note in the model where the information is complete, or what is missing.

Plan out how you are going to get it

Plan it out, have a digital camera to keep track of everything that you look at. I like to take a picture of the equipment number label, and then the nameplate. There is a column in our data collection sheets where you can add the image numbers to keep track of them later.

If you are consultant going to a site to gather data, make sure that you or your site contact coordinates with maintenance, and have someone from that department go around the site with you. They typically know the site and the equipment better than anyone else.

When you have a grasp on the information that you need, and what is missing, a plan can be put together to start gathering the rest of it in the field. Gathering data on live equipment can be a risky procedure, and be sure to consult your facilities electrical safety program on the best method to start. If your facility doesn't have an electrical safety program in place, and the power system study is supposed to help with the development of it, then working in an de-energized state is the most prudent way to go.

Take note of the current status of all switches, breakers etc. before you get in there, this is important to determine the "normal" operating situation for the model.

Get out into the field.

This can make it difficult to gather the information and open MCC buckets, etc, however it doesn't have to be all gathered at one time. Plan around existing outage and maintenance schedules to gather the information while the equipment is down already. If there is an unscheduled outage, before the equipment is re-energized consult with the operator to wait until the data is gathered, coordinate with the various teams in the field to gather the data in a piecemeal way as they are going about hteir normal work.

Make sure everyone is safe and not taking unnecessary risks

If you are using outside resources, they may have their own safety program in place, and be able to help expedite the process. It is very important to remember that opening equipment to develop a safety program is not the best way to get the information. If at all possible de-energize. It will take 5min or so per bucket. A scheduled shutdown will never take as long as one that is un-scheduled, especially if it causes an fault or arc flash event. That equipment will be unavailable longer, not to mention the possible injury to workers.

Data Quality

The quality of the infromation that you are gathering is critical to the development of the model. This is something we talked about in the first post of this series Data Collection For Power Series

"the results from the power system model are only as good as the data that is used to create it"

This is also talked about in the EasyPower Webinar - Garbage in Garbage Out. It is useful to check this out before starting the actual collection process.

https://www.youtube.com/watch?v=pMtmvkAxZVw[/embed]

What's Next

The last post in the series we will be talking about what is the data that you need to start putting together. It is important to hang around and check out that post.

Data Collection For Power System Studies

2015-03-02T07:26:00-04:00

What Is Needed When Gathering Data For Power System Studies

Data Collection is about gathering the data necessary for building an accurate model of your power system. This model will be the basis for the various studies that we mentioned last week, and without accurate data the model will not be as useful as you need it to be.

Why having complete and accurate data is important

First the results from the power system model are only as good as the data that is used to create it. If the data is not correct, then the model that is created will not be accurate. In fact incorrect data will lead to poor results in the incident energy study which is very sensitive to the fault levels on the system. It is very important to get accurate impedance information, this includes cable configurations, transformer data, etc.

Collecting the data for the first time is a very labour intensive prospect, and can account to 50% of the cost of getting the initial study completed. That's one of the reasons I mentioned before about getting the data together, and getting more than one report completed at the same time. The incremental cost in negligible compared to the total cost of the project.

When your facility has good single line diagrams, manuals, and data in other forms, this will speed up the collection process. However it is always a good idea to verify all this data in the field, especially for larger, active facilities where changes are being made on a constant basis. When this is completed once, the model can be used as a change management tool. One of the software vendors have a great webinar describing how you can use their software to manage change in the entire facility

https://www.youtube.com/watch?v=a_fJPEumoGw

How long to expect?

You can expect that the data gathering stage of the project will take about 2hours for every substation, switchgear lineup and MCC, and 0.1 hours for every load, including motors, panels, etc. If your facility is spread out or has a lot of specialty equipment these numbers may need to be increased. This will give you an idea on how long you can expect to take to gather all the data for your facility.

We have included forms in the content library that will help you gather this information. We based the information required on the recommendations of ETAP.

How much do you need to gather?

Depending on what set of studies you are planning to have completed, the detail of the data that needs to be gathered will be slightly different. It is my opinion that you have at least the 4 studies completed that we mentioned last week, they are Short Circuit, Protection Coordination, Incident Energy and Load Flow. These 4 studies build upon each other, and as such they need increasingly more and better detailed information. Lets start at the top, what do they all need?

Utility information (MVA, X/R min and max)
Nominal system voltage levels
System configuration with the following equipment: - Transformers (with impedance, voltage and configuration), - Configuration switches and circuit breakers - Switch gear, mccs, switchboards, etc down to the voltage level you are interested in
Any large motors and other generation on the site.

Power System Studies - The Why and How

2015-02-27T09:52:00-04:00

In the first part of the Power System Study series we talked about what a power system study is, and in the second I described why a power system analysis is critical for every facility, plant, building, etc, no matter how large or small.

These are:

Short Circuit
Protection Coordination
Incident Energy
Load Flow

Now, assuming you have these studies in your hands, what do you do with them? In Part 3 I will give ideas on why power system studies are important for your facility and business, and how different areas of you company can benefit from a comprehensive power system study.

Who can leverage a power system study

It's not just engineers

Once you have a power system study in place you can starting thinking about how to leverage it and make decisions to improve your facility.

There are four perspectives that the study can be viewed from, and most companies have them. Whether it is one person with many hats, or groups of dedicated personelle.

They are

Management
Operations,
Maintenance,
Capital projects.

Management

With the Incident Energy report in hand, critical information can be added to the Arc Flash Risk Assessment and areas that are found to be high risk can be looked at closely. Mitigation techniques can be implemented in these areas starting with eliminating the risk entirely, or adding engineering controls that lower the incident energy to an acceptable range.

This may be a relatively simple setting change in a relay, or replacing an old protection scheme with a modern relay with multiple sets of settings. One for normal operation and another for energized work.

Management will integrate this information into the facility's electrical safety program, and the general safety program. They can update the risk assessments associated with their electrical system.

Operations

Second,operations can use the reports to identify areas that are a higher risk to cause outages, and determine how the system reacts to faults. The two studies of particular interest are the protection coordination and incident energy.

The protection coordination lets the operator know what areas of the facility will be affected in the case of an outage, and if the area is too large, or not large enough, modifications can be made to optimize the selective coordination scheme.

The incident energy study helps the workers on the floor stay prepared, within the greater electrical safety program.

Maintenance

Maintenance will look at the short circuit and load flows to help prioritize where preventative maintenance budgets should be focused. The short circuit study will determine if there is any existing equipment that is over-dutied. Meaning that it is not designed to handle the fault currents that it could be subjected to in the event of a bolted fault. If there is any over-dutied equipment identified, maintenance will start the process of replacing, or mitigating the fault currents by changing system configuration, such as not operating with transformers in parallel, or adding current limiting reactors that increase the short circuit impedance on the system.

The load flow report can help schedule maintenance schedules for major equipment such as motors and distribution transformers. If a newer transformer is close to its design load most of the time, versus a older transformer being lightly loaded, the probability of failure may lean toward replacing the newer transformer before the older one. Without the load information the older transformer would be replaced sooner, costing more from the maintenance budget if the newer transformer failed around the same time.

Capital Projects

Finally capital projects can use the model to make improve decisions for capital improvements. When capital improvements are in the early stages, modifications to the greater power system, other than the new equipment being added, is sometimes neglected. This oversight may increase the cost greatly when the service entrance needs to be replaced, or other major changes have to be made.

With a current short circuit and load flow study, most of these issues can be accounted for early in the capital project cycle and power system improvements can be accounted for at the start. Without a current power system study you will not know, and it will likely cost too much to have one completed just for a capital project budgeting.

Along the same lines the model can be used to save money, one way is by making improvements to the power system to increase efficiency.

Utilities, especially when they are dealing with a large load, may have power factor and demand changes that are much higher that the energy charge. With a load flow study in hand, it is a relatively easy task to determine where pf correction could be added to keep the PF charges low, or if there are any buses in particular that can be controlled differently to prevent new demand charges.

Conclusion

This concludes our three part series on Power System Studies.

If you missed Part 1 on Monday, it defines what a Power System Study is, and Wednesday I talked about what the critical power system studies every facility needs.

Power System Studies - The Critical Four

2015-02-25T07:45:00-04:00

In the first part of the Power System Study series I told you what a power system study is, and what power system analysis I consider critical for every facility, plant, building, etc, no matter how large or small.

These are:

Short Circuit
Protection Coordination
Incident Energy
Load Flow

Power Systems The Fabulous Four

The reason these four studies are so powerful are that they require much of the same data, and when completed together they have the ability to save time and money, versus completing them one at a time. For example, the incident energy at a bus is determined by the amount of current in a fault and the time that current is present. That requires the Short Circuit and Protection Coordination studies to be completed.

Typically, a short circuit study doesn't require impedances other than transformers, however an incident energy study does. With this added information the majority of the data needed for a load flow study is already in the model. To complete the load flow you only need to add some loading scenarios at the various buses on your system.

Short Circuit Study

The purpose of the short circuit study is to determine the fault current available at the various buses on your system. These are worse case single and three phase bolted faults. The data required for this study in particular is the utility impedance, or how much energy can they supply to a fault, and the various transformers size and impedance. It is these impedances that are typically used to determine the magnitude of the fault current at any bus.

With this information you can determine if your equipment is sized appropriately (or if you are designing a new system, you can size the equipment appropriately) and will not fail during a fault event.

Protection Coordination Study

The purpose of the protection coordination study is the verify that the various protection devices in your system, relays, breakers, fuses, etc are coordinated correctly and are sized appropriately for the equipment that they are protecting. For example, this study would verify that a fault on a lighting panel will not activate the main breaker on to the facility, but rather activate the closest breaker to the fault, either the main breaker (or fuse) or the protection on the feed to the lighting panel.

Incident Energy Study

The incident energy study is (IE Study) one part of an Arc Flash Risk Assessment, it determines the thermal energy generated from an arcing fault. From this information the Arc Flash Boundary is determined and proper PPE can be selected for any energized work at that location.

NFPA 70E and CSA Z462 require an Arc Flash Risk Assessment be completed as part of a complete Electrical Safety Program. The incident energy system is one critical component of the Arc Flash Risk Assessment.

The magnitude of incident energy at a bus is proportional to the square of the arcing fault current and the time that it is present. The fault current is based on the currents determined in the short circuit study, typically 80% of the symmetrical short circuit value, and the protection coordination study will determine how long it will take for the arc fault to be cleared by protection.

This is a good place to mention, that all of these studies, by necessity, assume that the equipment has been installed and maintained per the local codes and manufacturers recommendations. If a 4160V breaker hasn't been exercised for the entire time that it has been installed, it may not operate as intended, and the calculations performed by these studies will have no value until the breaker operation has been verified.

Load Flow Study

Now for the hardest of all studies, the load flow study. As we know, a power system is very dynamic, and as such the exact load on a particular circuit is changing all the time. This makes it very difficult to determine the values required to make a perfect model. However that doesn't mean that you can't glean important information from it. With the help of your operators/building maintenance the engineer completing your study will be able to put together a few normal scenarios that can be used to get estimates of the loads and supplies on your system.

The information that is critical from a proper load flow is the voltages and power factor at all your buses, currents or power flow on all your feeders. With this information you will be able to make important decisions on where to add or remove load, and where power factor correction can be added to increase the efficiency of your system.

Power System Studies - The What

2015-02-23T06:43:00-04:00

Definition:

A group of studies used to analyze a power systems response to events over different time periods.

The time periods

There are three over all time periods that a power system study will look at, they are:

Transient
Dynamic
Static

Transient studies look at the over all power system response to an event over a very short period of time. This time period can be from a portion of a cycle to 1 or 2 seconds. An example of a transient study would be analyzing the system response of a capacitor bank being switched on to the system, and verifying that it won't introduce an instability.

Dynamic studies look at the power system response over seconds to a minute until the system has reached a new steady state. An example of a dynamic study is starting a large motor, line an ID Fan. Motors have high starting currents and can have major impacts on the system voltage.

Static studies review the system in a steady state and is used to report the values. Load Flows, also referred to as Power Flow studies are good examples of this. They are used to determine the voltages, currents, and power factor at all the buses and cables within the power system.

Studies includes in the Power System Analysis

There are many different studies that can be included in a Power System Study report, a few of the more common are:

Short Circuit
Protection Coordination
Incident Energy
Load Flow
Dynamic Motor Starting
Transient Stability
Power Quality
Harmonic Analysis

They all have a place in the report, but some are more used than others, for example the four studies that I recommend that all facilities have are:

Short Circuit
Protection Coordination
Incident Energy
Load Flow

With these studies a facility will have most of the information required to troubleshoot problems, control change management, improve operation, make better maintenance and capital decisions just to name a few.

Power System Study Report

When the power system report is generated, don't leave it on the shelf to gather dust. NFPA 70E and CSA Z462 both require that the incident energy study be maintained and updated at least once every five years. Also there is great information in the report that can be leveraged when making critical decisions in your day to day operation of your business.

This concludes part 1 of our series on Power System Studies, on Wednesday I will talk about what the purpose of the four studies I recommended are for, and then on Friday it will be all about how you can leverage them to make better decisions at your facility.

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What is CSA-Z462?

2015-02-15T10:00:00-04:00

If you're going to be doing any job involving electricity, it's important to know how to keep yourself safe. If you're looking for a standard and you live in Canada, then you have to look no farther than CSA Z462. source.

CSA Z462 is the Canadian Standard for Workplace Electrical Safety. It is developed in parallel with NFPA 70E: the American Standard for Electrical Safety in the Workplace.

The first edition of CSA Z462 was published in 2008. Prior to that, Canada did not have a specific standard related to electrical safety in the workplace. The Canadian Electrical Code existed, but was used for designing and installing electrical systems, and did not necessarily address safe electrical working practices. According to CSA group, in 2006, “On average, every day, five Canadians die as a result of work-related accidents and diseases… Canada currently ranks among the worst countries in the developed world in occupational health and safety”. “Across Canada in 2007 there were 472 known injuries with electric current on the job and nine fatalities. The previous year there were 567 injuries and 20 fatalities.” At the time, Canadians used an American standard for workplace electrical safety: NFPA 70E. The time had come for Canada to have its own electrical workplace safety standard tailored to suit Canadian federal and provincial regulations.

CSA Z462 is a CSA group standard: it is not enforced, but it is recommended for use by anyone in Canada working in an industry where energized electrical equipment is present. “It is intended for use with Parts I, II, III of the Canadian Electrical Code; and, has been harmonized with CAN/CSA-Z460, Control of hazardous energy — Lockout and other methods; and CAN/CSA-M421, Use of electricity in mines”.

For your electrical safety program, you must meet the requirements of the Canadian Labour Code as well as the requirements of any provincial legal regulations. The Canadian Labour Code and those provincial regulations will point you to the Canadian Electrical Code. The Canadian Electrical Code will point you to CSA Z462 as the minimum recommended standard for electrical workplace safety. In other words, if the Canadian Labour Code and provincial regulations tell you “what” your safety program needs to do, CSA Z462 tells you “how” to do it.

CSA Z462 covers electrical safety-related work practices, electrical safety-related maintenance requirements, and electrical safety requirements for special equipment. CSA Z462 is developed parallel to NFPA 70E, and in many cases uses the same data, calculations, and charts for things like personal protective equipment (PPE) and incident energy or arc flash boundary calculations. It is published and updated in conjunction with the Canadian Electrical Code, as well as CSA Z460 (Hazardous Energy Control) and the new Z463 Guideline on Maintenance of Electrical Systems.

The third and current edition of CSA Z462 is Z462-15. Published in 2015, the third edition brings a number of major changes, including:

Elimination of prohibited approach boundary and HRC Category "0"
Enhanced clarification of risk assessment procedures for hazardous electrical systems
Hierarchy of control applied to risk mitigation
Considerations on condition of equipment
New requirement for audits of field work
New section on human performance and electrical safety

The third edition also improves upon the previous edition with:

Improved direction on hazard identification and risk assessment
New safety procedures and assessment tables for work around DC systems
New tables for the selection of personal protective equipment
Added guidance on safe procedures and training
New Annexes on safety around high-voltage systems and electrostatic discharges
Updated with the 2015 Canadian Electrical Code and the new Z463 Guideline on Maintenance of Electrical Systems
Incorporates the principles and procedures detailed in the new Z463 Guideline on Maintenance of Electrical Systems
Updated in conjunction with updates of the CE Code and CSA Z460 (Hazardous Energy Control)
New criteria and advice on risk assessment and risk-based decision making

CSA Z462-15 has three major sections:

Safety-related work practices
Safety-related maintenance practices
Safety requirements for special equipment

As you might have noticed, the key similarity between all three of these major sections is safety. The current edition of CSA Z462 places a great emphasis on safety, including the development of an electrical safety program in conjunction with your workplace's occupational health and safety program. CSA Z462-15 also has a list of informative annexes, including one devoted specifically to electrical safety programs.

Electrical Safety at the office

2014-12-08T15:11:00-04:00

Electrical safety in an office is very similar to electrical safety at home, except for there is larger equipment and more people around. The tips for electrical safety at home were:

Watch for unapproved equipment
Don't overload circuits
and inspect your surroundings

At the Office

What is different from your office to your home? Mostly it's your surroundings, and how they are continuously changing. New employees, clients coming and going. New photocopiers, extension cords across the hall, and other equipment that you typically don't have at home.

Preventing Accidents

Electrical accidents that occur in an office environment are usually a result of faulty or defective equipment, unsafe installation, or misuse of equipment - specifically, extension cords, power strips, and surge protectors... {SOURCE}

The best way to stay safe at the office is to be aware of your surroundings, and complete casual inspections of your work area on a continual basis.

Things to look out for around your desk include:

Un-protected cords on the floor.

A lot of electrical shocks around the office or construction site are from damaged cords. Stretching an extension cord across the floor expose them to damage, and creates a shock hazard. If you have to use an extension cord, protect it. There are great products for this, search on Amazon.

Be sure that you are checking the cord from damage even when it is hidden, they can hide damage as well as protect them.

Don't store anything in front of electrical panels, or anything that has any electrical equipment in it.

I go to site more often than I like finding the "electrical room" turned into the janitor's closet, or general store room. The electrical panels need to have a minimum of 1m in front of them, and a clear path towards them. This is to allow proper and safe use of the panel when needed.

Plug space heaters into a dedicated receptacle, not the space bar.

Don't overload your power bars! Space heaters are a large corded load, when they are plugged into a power bar, you run the risk of overloading the bar, without tripping the breaker. This will cause a fire hazard as the power bar heats up.

Always use grounded plugs, and NEVER cut off the ground on a 3 prong plug.

This is not something that happens as much in newer offices, but you will see it when someone uses a cheap extension cord that isn't grounded. These are made for lamps and other ungrounded equipment, but are used for general purpose. If you have a 3 prong cord, ALWAYs use the 3 prongs. Never cut it off, or modify the extension cord "to make it work".

Office Electrical Safety Summary

Staying safe with electricity around the office is a lot of common sense - use equipment as its intended, don't use damaged equipment, don't modify cords, inspect your cords and keep your cords protected.

What are some of things you do to safe at work? Share them in the comments.

Electrical Safety and Arc Flash

2014-12-01T13:42:00-04:00

Electrical safety is a nebulous thing, but we define it as the set of systems designed to lower the risks associated with the electrical hazards of shock, arc flash and arc blast, to an acceptable level. In our day-to-day life this is handled for us, behind the scenes by the engineers and electrical workers designing, installing and testing the systems around us. The power system, from a users perspective is safe by design.

When interacting closely to the electrical systems around home and at work, we must start taking more precautions to ensure that we are not increasing the risk of injury. These risks are mitigated through a hierarchy of controls. These controls lower the risk to zero in a best case scenario, and to a level that an electrical worker deems acceptable otherwise.

Electrical Safety Program

Depending on your workplace, you may have an electrical safety program. The purpose of the electrical safety program is to educate the workers so they understand the hazards and risks they represent, and how to do field risk assessments. The electrical safety program will outline the various steps that have been taken to limit the risks to acceptable levels, and what the worker can do to ensure they work safe.

An electrical safety program will include training on the various labels that are throughout the facility, what the various hazards are, how to care for PPE, when PPE is required, what an energized work permit is, and why its important, and much more.

Arc Flash and Incident Energy

You will hear people use incident energy study and arc flash in the same breath, however they are two different things. The incident energy is only one of the potential causes of injury as a result of and arc flash event, the others include blindness, hearing loss, blunt force trauma, etc. The incident energy study only represents the potential heat energy associated with an arc flash event. An arc flash analysis however should holistically review a potential arc flash event and provide mitigation techniques that will limit all the results of the arc flash. The calculation of the incident energy is the most mature, however we have seen PPE recommendations evolve over the years as the sound and light hazards have become better understood.

One of the outputs of an arc flash analysis is the label. During orientation, or general electrical safety training, workers will be trained on reading the label and determine how to choose PPE for the task at hand. We develop arc flash analysis reports for our clients and if you would like to learn more you can learn more here - JMK Engineering Power System Analysis.

If you would like to learn how to develop an arc flash analysis for yourself, or someone else at your company, well we are putting together a course just to do this. It is still very much at the early stages, but if you would like to get emails as it is developed, and get a 75% discount head over to Arc Flash Course and add your email to the list.

What Does JMK Engineering do?

So you have made it this far, at JMK Engineering we analyze your power system, documentation, processes, etc and help you make decisions around capital spend regarding electrical safety. Rarely does a company have to start from scratch, it is more likely that all the information is available and it just has to be put in one spot, that all employees have access to. We will identify areas that you will need to improve to meet industry standards, provide an arc flash analysis (or update your existing) and work with other experts to ensure that you have a complete electrical safety program and a plan for continuous improvement. It is MUCH less important to have a complete electrical safety program at the onset, it is more important to have a process to continuously improve the systems and processes you have today.

No matter how small or bare-bones a system you start with, when you are continuously improve it on a monthly or quarterly or yearly basis, over time it will become one of the best in the business and perfectly fit your evolving business.

Incident Energy Studies

2014-11-27T06:48:00-04:00

Incident Energy: The amount of energy impressed on a surface, a certain distance from the source, generated during an electrical arc event. One of the units used to measure incident energy is calories per centimeter squared (cal/cm2).[1. National Fire Protection Association. 2008. NFPA 70E-2009: standard for electrical safety requirements for employee workplaces. (Quincy, MA): NFPA.]

When you hear arc flash and arc flash studies, what most people are really interested in is the incident energy portion of the study. This study helps employees, employers and all other interested parties determine the energy level, and the associated PPE required when working on a specific piece of equipment. Even if your facility or company doesn't do any live electrical work, these studies are important to have to verify that the energy has truly been isolated. Until the equipment has been verified to be de-energized, it must be assumed to be energized, and therefore a danger of an arc flash is possible.

An incident energy study is only one part of a complete power system analysis. The other portions of a complete power system analysis include:

Short Circuit Study
Protection Coordination
And Load Flow

The Information Needed

An incident energy (IE) study is something that has to be coordinated by the operator of the facility and the engineer developing the report. The operating conditions of the system can have very dramatic affects to the available incident energy at the location of the fault. The following factors must be considered when setting up the power system model when arc flash and their resultant incident energies are the intended outcome:

Available Short Circuit
Cable length, type and configuration
Protection Settings
And connected motors.

Cable Configuration and Length

Like mentioned above, impedance plays a large part in how much fault current is available. When designing a power system, the short circuit current may be calculated with either very large or no cables, using the transformer as the only impedance. When the short circuit study is completed with this data, the bolted fault and therefore the arcing fault will be much less.

Short Circuit

The available short circuit at a particular bus is determined by the short circuit study. The two factors that determine the available energy are, the amount of current and the amount of time that it is there.

The short circuit current is determined using calculations assuming a bolted fault, like a bus bar has been bolted to the bus and the power turned on. Since an arcing fault has an impedance the maximum power in an arcing fault is Parc = Pbolted x 0.707^2, or about half.

Protection Settings

Like with the short circuit, protection settings may be initial designed assuming bolted faults with little to no cable information. When the cable information is added, the available fault is much less, and therefore the protection settings may need to be tightened. Parc is just one variable in the incident energy equation, the other is time. If the protection is electrically far away from the actual arcing fault, it won't be tripped for a longer period, increasing the incident energy without added reliability.

Connected Motors

When motors are disconnected while they are running, they become generators and the voltage is increased over the gap. If there is an arc, this lessens the impedance (over free air) and current will be supplied into the arc from the motors for a short period of time. This time is determined by the inertial load on the motor, and the size of the motor. For example a larger motor will supply more energy into the fault, and have a larger inertia than a smaller one.

We like to include any motors that are above 25hp in the model and then lump the other connected motor according the load calculator in the Canadian Electrical Code. This allows us to get an accurate picture of what the motors will contribute to the fault.

Operation Data

We mentioned above that it is important to have operations involved from the start, this is because the configuration of the system is very important when determining the incident energy in the case of an arc fault. While getting the worse case short circuit is relatively easy, determining the worse case with regards to incident energy is much harder. The load on the system, how loaded large motors are, what transformers are connected, etc have large impacts on the overall system impedance.

To get the correct data in the report, various operational "norms" need to be compared, and these normal system configurations will be provided by the operations team at the facility. If there is a special configuration during live work, this must be taken into consideration before work begins, and the engineer must be informed so they can determine if this will be a new worse case. A large system may have too many possible configurations to account for at the time of the study, therefore only the regular operating configurations may be looked at.

Conclusion

Incident Energy Studies are an important tool in operating a safe and reliable electrical power system. In the coming weeks we will explain the other power system analysis components mentioned here, Short Circuit and Protection, and add on more Load Flow.

3 tips to use electricity safely at home

2014-11-24T06:53:00-04:00

The more connected we become, and the more DIY projects we take on, the more aware we need to be of the hazards of electricity. There are two hazards directly associated with electricity: shock and arc flash. This said, there are many more indirect electrical hazards that can arise from misapplication, such has heat causing fire from overloaded circuits.

Staying safe with electricity at home is really easy; you should never do electrical work by yourself. Always have a qualified electrician do any work in your home if it requires removing a plate or fixture. There are three things that you need to do to stay safer at home:

1 Only plug in approved appliances

Counterfeiting is a much larger concern in Canada than most realize. This has nothing to do with that movie you downloaded in university (or last night). We are talking about counterfeiters importing common electrical equipment like phone chargers, lamps, etc. These devices are likely not approved, tested or suitable for use. They may over heat and cause fires, or become a shock hazard.

Whenever you buy something to be plugged into a wall outlet, be sure that the device has a suitable, approved mark. For example, ESA in Ontario has a great list of all the recognized certification marks in Ontario http://www.esasafe.com/consumers/productsafety/marks

2 Don't overload your circuits

In North America, the typical wiring in a house is designed to carry 15 Amps - anything above that will cause the breaker for that circuit to trip. The wire in an extension cord or power bar, on the other hand, is designed to carry much less, depending on the gauge of wire used. Overloaded wires will heat up, and can cause fires.

3 Household safety inspections

Develop a routine where you go around the home and check your various electrical components to be sure they are still safe for use. This includes the cords on your TV, appliances, lamps, etc, any extension cords and your GFCI and AFCI breakers and receptacles

Inspect all your cords. Look for damage to the cord in the form of nicks, scratches or bare wires. A cord that is warm to the touch is a sign of overheating. In the case of an extension cord, unplug and replace it, or have a licensed electrician fix or replace the cord. When discarding, be sure to cut the cord through to ensure that an unsuspecting person doesn't try to use the defective equipment. Test your GFCI receptacles by pushing the TEST button. If it works properly you will hear a click and the power will be turned off. Press the reset to put back into service. If you have GFCIs in your panel, do the same thing. If it is working, you will see the breaker trip.

Reset the breaker and you are done.

AFCI breakers and receptacles are tested in the same way as GFCI.

Electrical Safety in General

https://www.youtube.com/watch?v=gGQHfb83Kao

In general, electrical safety at home is all about using certified/marked appliances, with maintained cords, without overloading the circuits at home. By doing this you will lessen your chance of an electrical fire, or shock to you or your loved ones.

Holiday Safety from the ESA

2014-11-17T15:16:00-04:00

The Ontario Electrical Safety Association (@homeandsafety) has a great video on Holiday Electrical Safety. Worth the watch before you put up your Christmas Ornaments this weekend.

https://www.youtube.com/watch?v=jZqyIqjFq84

Stay safe this holiday season.

Introduction to Power Systems

2014-10-21T17:54:00-03:00

What are Power Systems

Describe what a power system is and link to a better post

Talk about 3 phase power and a short history of it.

Talk about the different voltages and link to the better post.

Blurb about design and interpretation of how a power system reacts using power system studies.

Power System Studies

Power System studies are a group of studies that look at a power system model developed in various software, or by hand, that tell something about how the system operates.

There are various types of these studies, including:

Short Circuit Study
Time-Current Curve (TCC) Study
Load Flow Study
Incident Energy Study

These 4 are the most common types and with them an engineer can glean a lot of the information they need to determine the state of the system in a moment in time. That is a critical distinction, these studies are snapshots in time of how the system is configured, a load change in a motor will change how the entire system behaves. A competent engineer will be able to determine the worse case set up for the system, especially in the area that they are looking at, to determine what the best group of scenarios are to set up the initial state. It is a iterative process.

Short Circuit Study

A Short Circuit Study is used to determine if the bracing is proper in the event that there is a solid short circuit (bolted fault) across the phases or a phase to ground. This creates large amounts of current, and the various magnetic fields that come with them.

TCC Study

A TCC study coordinates the protection on the system such that the closest protection device to the fault will trip. This ensures that the least amount of equipment is affected in the occurrence of a fault on the system. It also helps determine how the system will react during an event in a predictable manner.

There is always an interplay between the TCC and Incident Energy studies. Sometimes we will sacrifice coordination for lower incident energy levels.

Incident Energy Study

This is the study that is also referred to as a arc flash study. This study helps determine the incident energy levels in the case of an arc fault using IEEE or NFPA equations.

Load Flow Study

This is the most fluid and changing study. Here you set up the system with the known loads and determine how the power flow is affected across the system, current, power factor, and voltage.

This study is important in determining if power factor correction is necessary, and how to go about it. If the feeders are sized properly to minimize voltage drop and ampacity.