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Anonymous Poster

Calculation for Short Circuit Current

11/15/2010 1:34 AM

Dear Sir ,

1) How To calcualtion Short Circuit Current For VCB ( Circuit Breaker )

Rating is 12 kv , 1250 amps, 26.3 ka ?

2) In circuit Breaker close Spring & Tripping Spring Using in Operation conduction Closing Spring Load Only added or Tripping Spring Load also added ?

3) What Is differnce Bettween Blot Grade 4.4 & 8.8 ?
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kvsridhar
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#1

Re: Calcualtion for Short Circuit Current

11/15/2010 4:56 AM

i am not sure i have understood your question, however, for what it is worth.....

1) The Short-circuit current = 26.3 kA... so what's your doubt?

2) Closing spring gives the energy to close the CB, and opening spring helps in quick opening when the CB trips. Both are required.

3) Grade 8.8 bolts are stronger. i haven't come across 4.4, only 4.6 and 4.8. Here is a link : http://www.roymech.co.uk/Useful_Tables/Screws/Strength.htm

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asadmawa
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Join Date: Oct 2010
Location: Libya(Bangladeshi)
Posts: 15
#2

Re: Calcualtion for Short Circuit Current

11/15/2010 9:59 AM

1.You have to calculate the short circuit current for your system(load),

then you can buy VCB ,so that its breaking capacity(KA) must be greater than your calculated short circuit current.

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wareagle
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Join Date: Jun 2008
Location: Alabama
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#3

Re: Calcualtion for Short Circuit Current

11/15/2010 1:48 PM

Question "How To calcualtion Short Circuit Current For VCB ( Circuit Breaker )"

correct way http://ecmweb.com/mag/electric_shortcircuit_calculation_methods/?smte=wr

easy way http://ecmweb.com/mag/electric_making_shortcircuit_calculations/index.html
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