Respected sir's,

Please clear my doubts?
How to calculate the "short time current rating"(i.e-primary short time current rating-like if u take 400-400/5-15va/class1,40ka/3sec).


40ka/3sec-how to calculate this rating from the substation?
Is there any formula?please advise me...

I am waiting for your's reply...


Thanks&regards,
pandees.b

Short time rating is defined by your MVA rating. Suppose you are using 0.8MVA transformer at 33/11KV, so your STC will be 0.8*1000/(1.73*11)=42KA.

I hope this will help you. So to calculate STC the data you have given is not useful.. but system parameters are required.

How much will be 6.6 /.4 kv transformer be equivalent in KVA

Not enough information provided, assuming you mean the primary is 6.6kV and the secondaray is .4 kV.

Quote:

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Originally Posted by kkspwr

how much will be 6.6 /.4 kv transformer be equivalent in KVA

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Study some electrical man , you are technically too weak to suggest , are you aware of % impedance?