Dear Sirs,
I am a technical persons.In one of our Electrical Sub-
Station, We have installed three numbers of
1250KVA ,11KV/0.415KV Transformer to feed the Factory load.
We have found some abnormality. In one of our Transformers
the leakeage current from transformer body to earth through
earth continuity wire is almost 86 Amp but in other
transformer it is (5-10)Amp. where the load current on
three phase and neutral are respectively
1360Amp,1400Amp,1370 Amp & 176Amp. So please any technical
person help me about the reasons of this situation and how
I can rectify the fault. Moreover,I have measured the earth
resistance of the Earth continuity wire which is less than
1 Ohm.

Thanks

Tapas Barua

Answer Posted / sreenu

Hi dear,

Pls check the differential relay is not working properly, if its work this problem not faced. Pls check the primary current is equal to secondary current more than 30 times to the secondary winding.

Ex; if u have 2500kva transformer gives secondary current as per designing it vl gv 3477Amps is equal to primary current. Both r matches their is no problems transformer.

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