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mahdi hossaini
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Join Date: Jul 2012
Posts: 8

Power Electrical Engineering

07/21/2012 4:34 AM

why do the standard consider 3 Seconds for short circuit withstand current of 63/20KV Substation,and 1 Second for 400, 230KV Substation?

why don't we consider 1 Second for 63/20KV Substation?
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Bibo92004
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Join Date: Jul 2011
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#1

Re: power Electrical Engineering

07/21/2012 7:42 AM

Which standards did you get that from?
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JRaef
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United States - Member - New Member Engineering Fields - Power Engineering - New Member

Join Date: Sep 2006
Location: California, USA, where the Godless live next door to God.
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#2

Re: power Electrical Engineering

07/21/2012 10:55 AM

Because if you have a fault at the 400V tier, and it takes 1 second for the 400V protective device to clear it, the higher tier system has to stay in a little longer, otherwise the fault interruption spreads further. But at the 230kV tier, it is assumed there is a lot of impedance between it and any possible down stream fault so a lower tier fault will be dampened, but if a fault happens AT the 230kV tier, you want to clear it fast.

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bigg
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#3

Re: power Electrical Engineering

07/21/2012 11:19 AM

You wouldn't happen to be Anonymous Poster, would you?

http://cr4.globalspec.com/thread/79349/Electrical-Engineering
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FLIPFLOP
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Join Date: May 2009
Location: Kansas City, Missouri
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#4

Re: Power Electrical Engineering

07/21/2012 7:33 PM

rule of thumb: fault clearing time == 2-3 cycles for almost all systems.

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electricalexpert65
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#5

Re: Power Electrical Engineering

07/29/2012 9:04 AM

Which Standard says so?
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Bibo92004 (1); bigg (1); electricalexpert65 (1); FLIPFLOP (1); JRaef (1)

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