why transformer rated in KVA not in KW ? we know that W= v*i

Answer Posted / praveen420

rated transformer o/p is limited by heating and hence by the losses in transformer.mainly two type of losses occur in transformer iron loss and copper loss.iron loss depend on voltage and cu loss on current(amp)and these are almost unaffected by load pf so rating of transformer expp.in kva,va rather than kw.
w=v*i*cos(angle) in case of AC.
w=v*i in case of DC

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