CAN ANYONE HELP ME FOR FINDING SHORT CIRCUIT CURRENT AT THE LV SIDE?

I'm assuming you're looking for Isc on the LV side of a transformer:

For 3 Phase Isc = KVA/(Sqrt (3) * V L-L * Z)

For 1 Phase Isc = KVA (V L-L *Z)

Where KVA Is the transformer KVA rating

V L-L is the line-to-line voltage

and Z is the transformer impedance, i.e., Z=2% then the value used above would be 0.02

All of this should be available from the transformer nameplate

I believe that in the second equation the "/" was left out and you meant to say:

For 1 Phase Isc = KVA/(V L-L*Z).

These equations give the maximum possible short circuit current, assuming an infinite source on the other side of the transformer. This type of assumption is safe, in engineering terms, because if you design to this specification, actual fault currents will always be less.

JMM

thanks for ur reply

then how to find the impedence in the network?

for example

1500kva, 400v transformer 11/0.4kv

Please Please elaborate......I completely forgot to bring my Crystal Ball to work today....its in my other shorts!!!!!

Sorry.

Yes.You can do it with the Short circuit test.Connect a ammeter with secondary winding.It will show you u the value.For Brief discussion follow "Electrical Machines & Transformer" by Iriving.L.Cossow.Plz don"t forget to send your feedback.