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 Post subject: Process Improvment: Arc Flash Study Data Collection
PostPosted: Thu Jun 09, 2016 6:57 am 
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Joined: Fri Feb 13, 2015 9:27 am
Posts: 8
Location: Hendersonville, TN
So how does everyone collect the data for arc flash analysis? We still do ours the old fashion way by getting all the cable sizes, breaker, trip unit and fuse data, etc by opening equipment and basically hand sketching the distribution of the facility. As the standards have changed and we drive down deeper into the distribution system this seems to be very time consuming.
It seems if a customer has drawings they are outdated so that isn't always a dependable way to get accurate data. Taking pictures of panels, mcc's, etc seems to be easier on the surface, but you need a good way to catalog all that info as well so when you enter it into the software you know which breakers go with which panel, or which trip unit data goes with which breaker etc. Just curious how others approach this. Thanks


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 Post subject: Re: Process Improvment: Arc Flash Study Data Collection
PostPosted: Thu Jun 09, 2016 7:25 am 
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Location: Rutland, VT
We still do the data collection the same way you apparently do also. I think, while time consuming, it is the most accurate way and as you said if there are drawings they are out of date, but can be a starting point.

In some older facilities, things are either not labeled, equipment changed but old names still on breakers, or nothing labeled so we create a naming system.

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 Post subject: Re: Process Improvment: Arc Flash Study Data Collection
PostPosted: Thu Jun 09, 2016 7:54 am 
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Drawings generally do not contain all the information that is needed. For instance you might find cable schedules but those won't have breaker and fuse sizes and settings. Typically the latter may be on a single line or may be in a completely separate drawing. Transformer information is usually just the kVA and voltages at best on a drawing. Even if you have transformer name plate data unless someone has field verified it, it is often whatever the specification called for or whatever the manufacturer predicted it would be on the quote...the actual value is measured and stamped on the production line when it goes through final testing. It depends on the customer as well. If the customer wants 100% inspection, it's their money.

On a 5 year update it gets better. At this point you can walk out and use the original arc flash study as a starting point and do inspections. Part of the purpose of the inspections should be to assess the maintenance condition of the equipment as well as the validity of the information database (drawing). Usually you will see variation either in terms of a particular type of information (do all breaker settings match the drawing, do all fuse sizes match the drawing), as well as differences within maintenance crews. So if you know the maintenance organization structure, there is usually consistency there. Finally consider equipment age...may want to do 100% inspection on equipment that has been installed or substantially modified in the past 5 years. Also consider whether or not you are doing a condition of maintenance inspection which you need to make any claims about the accuracy of the results and/or to do a risk assessment.

What you will find is for instance some (or all) crews that routinely change fuse or breaker sizes without documenting it, or that the previous study did not do an adequate job in certain areas or certain tasks. The goal is to assess how much needs to be done. If you inspect 20 items (for an area, for a type of data) and get a 100% match, and you repeat this type of inspection in each area and for each type of equipment (randomizing it between low/medium/high voltage, etc., while still giving overall coverage...and you pick the area, not the customer), you'll get strong confidence as to whether or not the drawing is right.

In the last one of these I was involved with I was told that the information in area A was probably all garbage but that they knew that the information in area B was probably 99% correct except for a few areas that had been modified, and that the information in area C would be 100% correct. What was actually found was that area A was 100% correct, the information in area B was about 50% correct, and the information in area C was 80% correct. So we spent a lot of time "sampling" in area A just to verify that we kept getting correct information, and only had to do 100% inspections for part of the data for area C, but needed 100% inspections for area B.


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 Post subject: Re: Process Improvment: Arc Flash Study Data Collection
PostPosted: Thu Jun 09, 2016 9:33 am 
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Joined: Fri Feb 13, 2015 9:27 am
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Location: Hendersonville, TN
wbd wrote:
We still do the data collection the same way you apparently do also. I think, while time consuming, it is the most accurate way and as you said if there are drawings they are out of date, but can be a starting point.

In some older facilities, things are either not labeled, equipment changed but old names still on breakers, or nothing labeled so we create a naming system.



Agreed, we have found that the only way to get accurate data is to look at as much as possible in the field. I would say probably 70% of the places we go in have decent labeling but it is very time consuming when panel schedules are not correct. At that point you have to start tracing conduits to find what a circuit feeds. When it is industrial, where conduits are visible, it isn't nearly as bad as say a hospital where you have to trace out conduits in drop ceilings.
We collect data all the way down to the equipment level, so some of these project are very large. I believe some companies use generic labels for field disconnects or combination starters etc. We have always stayed away from that for accuracy purposes.


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 Post subject: Re: Process Improvment: Arc Flash Study Data Collection
PostPosted: Thu Jun 09, 2016 10:27 am 
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There is a point where you can "cut off" the data collection. Most power systems, even "rings" are essentially shaped like a tree. The vast majority of the power distribution system is then at the leaves, not the "trunk". So in terms of inspection time the vast bulk of the labor is capturing "leaves" and not the trunk.

There are basically 2 places where you can do this:
1. As you work your way down the distribution tree within a single voltage, eventually a branch will get to the minimum arc flash standard for the site (such as 1.2 or 2.0 cal/cm2 or for FR-required industries such as oil refineries, generally 4.0 cal/cm2). After that point only motor contributions matter (and usually not even then). A "rule of thumb" (with supporting data) was thrown out on this forum years ago that suggested that you'll never get above 1.2 cal/cm2 if the breaker size is 50 A or less. So far I haven't found any violations of that rule. Two caveats to watch out for:
A. Do not rely on this rule when you cross a transformer. As the voltage changes, the incident energy will change and usually goes up substantially.
B. Be aware of where you are at on the curve with the overcurrent protection device. If you are in an inverse time region, as impedance increases, incident energy also increases because time is increasing at a faster rate compared to current decreasing. Usually the effect is small but can be substantial.
2. Once you get down to 250 VAC or less generally this is more of a table or worst-case approach since IEEE 1584 at this point produces questionable results (only one test achieved an arc at 208 V and one voltage and one gap from the original 2002 data set). This level tends to be more "rule based".


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 Post subject: Re: Process Improvment: Arc Flash Study Data Collection
PostPosted: Mon Jun 13, 2016 7:48 am 
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I still prefer the old fashioned way of sketches and data in a notebook. I've tried the iPad, but haven't gotten proficient enough to do it quickly. Even if I'm taking photos, I make a sketch of the 1-Line so I can follow how things are connected later and the feeder size/type/insulation.

Photos: Photos are good for getting data on panels with the caveat, that they don't always focus well. So make sure the photo is focused before moving on.

What I do is take a series of photos per panel. I'm careful to not shoot anything else until I'm done with the series. The first photo is of the identification which I use as the marker for all of the photos to follow. If the panel does not have an identification nameplate, I use my sharpie and create an ID. That's important for when you come back later to put labels on. I also, make a sketch of the building if I don't have plans and mark the location on the sketch. 2) Long shot showing raceways up/down, 3) Panel nameplate, 4) Close up of the breaker area, 5) If previous wasn't clear enough to get ampere sizes, then one that is closer to get that, 6) Branch circuit directory 7) Main CB if one, making sure if it's electronic trip we can get the trip unit data and settings. 8) The sticker with the SC and Branch CB information. 9) If we can't get branch CB or main CB information from that, we take the dead-front off and attempt to get a photo of that information from the cb sticker. Similar process for other equipment like switchboards, MCC's, etc.

This next part is important. When you get back to the office, and download the photos, you create a folder for each panel (or switchboard, MCC, etc.). Then go through each photo and place them in the appropriate folder. This takes some time, usually 10-60 minutes depending how many panels you looked at. When you got 10, 20, or 50 panels, this last step will save you boatloads of time later when you're inputting data into your model.


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 Post subject: Re: Process Improvment: Arc Flash Study Data Collection
PostPosted: Mon Jun 13, 2016 9:59 am 
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Joined: Sat Apr 04, 2009 9:50 pm
Posts: 89
Location: San Antonio, TX
I started to do data collection for arc flash purposes on 2005. Two years later I decided that I would stop documenting the data in paper and bough Motion Computing tables (with Windows and SKM software installed).

So, from that moment, data collection and input data, is a one step the data process. I do not use paper anymore.

Additionally, I also take pictures in a very structured way, so it is very easy to catalog them at the end of each day. Then we add link to these pictures on our single line diagrams.

We have several tables, all with SKM software, and several engineers trained to collect data for arc flash and load flow purposes, and extremely faimiliar with SKM software.

I has worked very well and several customers now require this process from all vendors.


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 Post subject: Re: Process Improvment: Arc Flash Study Data Collection
PostPosted: Mon Jun 27, 2016 6:37 am 
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We do it the tried and true way. We've tried several methods, but always return to pencil and paper. We take lots of photos and number then to match the particular device. then they are linked thru the soft ware. Even the best survey person often can't read labels on breakers. We see 6 point and smaller font on labels. We've found good digital photos that are well focused in high resolution is best. The only issue is storing the survey data that takes up space.


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 Post subject: Re: Process Improvment: Arc Flash Study Data Collection
PostPosted: Mon Jun 27, 2016 10:02 am 
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Joined: Sat Apr 04, 2009 9:50 pm
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Location: San Antonio, TX
We have been doing data survey for arc flash purposes since 2005 (11 years). I used the "tried and true way of paper and pencil" for about 2-1/2 years before switching to a tablet and inputting the information directly in the software database. This improved the quality of the survey TREMENDOUSLY. Data input on the field has some useful data checking capabilities that tell you that something is incorrectly entered. Also, the interpretation issue from the person that collects the information in paper and then (probably another person) inputting the information on the software is prone for major inaccuracies.

I can go on for a long time promoting this new and more efficient way of doing the sensitive work of data collection for an AFHA.

The fact is that I have about 400 arc flash studies done with this method, with satisfied clients. Therefore, at least for my company, the use of tablet to collect field information is the "tried and true way".

If you have any questions, please call me and I can give you more details on how I do the surveys. Or you can attend the arc flash seminar (Course 202) delivered by me in behalf of SKM. See the SKM web site under training.


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