JMK Engineering Inc.

Solving problems and asking the right questions

Data Gathering

Executing a Power System Study at a pulp and paper mill

· · Leave a Comment

Industrial Paper Mill along a riverbank
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

scope_fig3Most 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.
Electrical panel maintenanceIt 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.

Electrical Safety Program: Getting Started

· · Leave a Comment

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.

Dust off that calculator because it's time to gather some data!
Dust off that calculator because it’s time to gather some data!

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 just these questions though: you should also look at anything specific to your workplace that isn’t listed above. Once you’ve gathered all possible information on the current safety practices of your workplace, you can get started with the creation of your new electrical safety program.
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.

This is part of our Electrical Safety Program Series.

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.
 

Data Requirements for Power System Studies

· · Leave a Comment

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.

Pole mounted utility transformers.
The size and type of the utility transformers make a huge difference

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 pLineup ready to start gathering data for a power system study.lay.
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.
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.

Plan you Data Collection Effort

· · Leave a Comment

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.

Data Collection Planning
Getting the Planning Process Together

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.
In the content library we have developed data gathering sheets that you can use to help organize your thoughts, and start filling out 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, the data sheets in the SparkyResource library is one way, 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.

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.  Be sure to be kept up on the posts by following us on Twitter and like our page on Facebook. And if you liked this article be sure to share with the buttons below and sign up for our newsletter (the form is below) where you will get these posts in your inbox and special offers.

Data Collection For Power System Studies

· · Leave a Comment

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.

Time to stat gathering that data.
Time to stat gathering that data.

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

How long to expect?

Data Collection can cost a lot of money
Managing cost and time is important

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 in, The Critical 4, 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.

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.

What’s Coming Up

On Wednesday I will lay out the specific data that is required for each of those critical four.  They all build upon each other, and will require collecting data in the field and interviewing operators and maintenance to understand how the facility operates.
If you liked this article be sure to share with the buttons below and sign up for our newsletter (the form is below) 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.

Check out our newsletter