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 Post subject: Fault Current Calculations
PostPosted: Mon Oct 05, 2009 1:55 pm 
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Location: OH
What software program or what is the recommended way to calculate fault current? Every program I use to calculate fault current has a different answer. Thanks for the replies.


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PostPosted: Mon Oct 05, 2009 2:07 pm 
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Joined: Sun Dec 23, 2007 1:44 pm
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Location: Charlotte, NC
Make sure the circuit/equipment configuration is the same and check them with hand calcs.


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PostPosted: Mon Oct 05, 2009 2:20 pm 
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I did check with a hand calculation. Results vary from a couple hundred amps or a little more. Am I being to critical? Should I use MVA, Ohmic, and include X/R ratios? How about the methods published by Bussman? Bussman has a free program to calculate fault currents. Can this method be trusted?


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PostPosted: Mon Oct 05, 2009 2:49 pm 
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Joined: Sun Dec 23, 2007 1:44 pm
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Location: Charlotte, NC
When you input basic info to a vendor program, that calc is made based on the developer's assumptions, but when you hand calc with specific x/r and sequence impedances, you get a more accurate result. If you are talking about the difference of say....20,000 amps or 20,200, what's the difference? I would say yes, that's a bit picky.

We are not that good anyway! :)

The key is to gather all available data, make any assumptions necessary, and understand the impact those assumptions may have on your results.

I normally use the per unit method and actual x/r ratios.


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PostPosted: Mon Oct 05, 2009 2:54 pm 
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Thanks for the reply. You answered my questions.


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