Answer / d.ramesh classes

efficiency of transformer depends on core loss and copper loss. core loss depends mainly on voltage and copper loss depends on current passing through the winding. so basically total loss i.e. efficiency depends on voltage and current that's why we rate transformer in KVA.

by D.RAMESH CLASSES

Answer / abhishek maji

Transformers ratings are given in kVA because the operating power factor of a transformer depends on the load,it is not constant rather varies with load...Secondly if it is rated in kW then as the operating power factor is not known in advance so operating current may be more than its rated current which may affect the winding insulation due to additional heating......Thirdly a transformer acts as an interfacing device between the power generating station and the load center and as my load not only demands active power but also requires reactive power so a transformer must have the capability of handling both types of powers.. that's another reason why transformers ratings are in kVA...

Answer / lakhan.self

Transformer is a static device which transfer the power from primary to secondry winding without change in frequency. So VA is unit of apperent power by means power is same ie VA in both side so Transformer rating is in KVA.

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