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 Post subject: Arc Flash at end load
PostPosted: Mon Apr 19, 2021 12:41 pm 

Joined: Mon Apr 19, 2021 12:13 pm
Posts: 1
Two questions:
1) What is done with arc flash data at the end loads?
Arc flash analysis software (SKM my case) gives arc flash levels at every end load. In the plant model, the intent is to have every 3 phase load is put into the model of the plant, and all single phase panels are also in the model (1500 buses and climbing as more of the panel loads are added). In SKM, if you have a bus, you have arc flash level in the reports. What are we supposed to do with the results? Put labels every motor, pump, heater, light, etc? It seems NFPA 70E calls for labels at switchboards/MCCs etc, but not end loads. What am I supposed to do with the arc flash level at the end load?

2) What electrode layout and box configuration do I use at these end loads?
The electrode layout and box dimensions is random and largely a guess in these loads (I do not work at the plant and cannot inspect the loads). Also, the configurations do not fall well into the arrangements of electrodes and boxes that IEEE 1584 is built around. What configuration is appropriate to enter into SKM?


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 Post subject: Re: Arc Flash at end load
PostPosted: Tue Apr 20, 2021 7:31 am 

Joined: Thu Apr 18, 2019 11:42 am
Posts: 45
A couple of things:

1) IEEE 1584 is relevant to three phase systems. It's ok to have the single phase portions of the electrical distribution system in the model for short circuit calc's, etc. but just know the AF calc's aren't exactly applicable. I believe there is discussion in one of the Annexes about single phase equivalents...

2) Do you have a copy of the 1584 standard? some judgment is required as to what gets labels and what doesn't. For example, I wouldn't put a label on a 5hp motor peckerhead, although I would put a label on a large machine that has an integral disconnect.

Mike


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 Post subject: Re: Arc Flash at end load
PostPosted: Thu Apr 22, 2021 1:31 pm 

Joined: Wed Jul 12, 2017 6:06 am
Posts: 35
If you have a bus you want in the model, but do not need an arc flash label for it, just exclude that bus from the study and it will not generate a label for it nor will it appear in the arc flash spreadsheet. However, as has already been mentioned, IEEE1584 can answer a lot of your questions.


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