I am working on a 11KV system with fault current of 40KA for 1 second. I have

I am working on a 11KV system with fault current of 40KA
for 1 second. I have selected 2500MVA 11/0.433KV
transformer.
How can i find the impedance value for this transformer?
Please help me.

Question Posted / bala

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I am working on a 11KV system with fault current of 40KA for 1 second. I have selected 2500MVA 11/..

Answer / wareagle

First I do not believe an 11 kv system can have a 40ka
fault. You need to check again.
Second I do not believe you can connect a 2500 mva
transformer to an 11 kv system. Maybe 2500 kva.
%Impedance is on the nameplate of the transformer or ask
the manufacturer.

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I am working on a 11KV system with fault current of 40KA for 1 second. I have selected 2500MVA 11/..

Answer / kaushik

i don't understand the purpose of giving 1 second ......
but what i think solution will be
s.c mva=1.732*v*i.
s.c mva=1.732*11000*40000.
s.c mva=762.08 mva.
per unit impedence of the transformer will be= (base
mva)/(s.c mva)
taking transformer 2500kva(i think it is wrong 2500mva)
we get
=(2.5/762)*100=0.328% of tranformer impedence

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