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ekstra   ara
 Post subject: Utility Modeling for arc Flash study
PostPosted: Wed Mar 26, 2008 9:46 pm 

Joined: Mon Jan 21, 2008 6:29 am
Posts: 1
Location: INDIA
hi friends,
i am on the job of Arc Flash study of 1 industrial setup.
The given fault values contains max & min values & cooorosponding X/R ratio as mentioned below:

Utility Fault levels are given with following details:
Supply voltage : 440V Freq:50 hz

Utility Fault level :
3 phase :- Max : 13kA , Min : 8.6kA
1 phase :- Max : 8.8kA , Min :1.9kA

X/R Ratio :
3 phase :- Max : 3.62 , Min : 0.329
1 phase :- Max : 3.31 , Min : 0.22

So, my questions is, how to model the utility for Arc Flash studies?

Is it required to model two utilities with 1 with max fault level & 1 with min fault level & corrosponding X/R ratio ; one is operating at a time.

Please advise?


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PostPosted: Fri Mar 28, 2008 3:19 pm 

Joined: Mon Sep 24, 2007 7:10 pm
Posts: 16
Location: Washington
Your software may allow you to model the system for both scenarios without requiring you to model the system twice. If you use the IEEE 1584 equations, there is a built in (reduced fault current) check that will evaluate 100% and 85% of fault current. If you model both the high and low estimate at both 100% and 85%, you will have a sufficient analysis. I don’t know if this is an option in all available software packages but this is an option in the Easy Power software.


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