Why the transformers are rated in KVA. ? in new view.

Question Posted / pradyumna171

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Why the transformers are rated in KVA. ? in new view...

Answer / pradyumna171

Power given to the transformer is Apparent power (K)
it is the supply power of the power house and the power
given by the transformer to the Load is the true power or
Active power which is actual used by the load and rest is
the reactive power i.e. square of apparent power including
iron loss & copper loss in KVA = square of true power in KW
+ square of reactive power in KVAR. A sound transformer
efficiency is 98% (input power- Iron loss (k) & copper loss
= output power).
For full resistive load (at unity pf ) a 100 KVA
transformer gives 100 KW (approx.) true power, and for
inductive power at .8 pf the same will able to give 80 KW
(approx.) true power, but the types of load (its pf) is not
know before which to be connected across the transformer,
this is only why the transformers are rated in KVA and it
is meaningless to discuss about the iron loss and copper
loss because the Inventor and UPS are also rated in
KVA.

In other hand or in simply we can
say due to unknowing power factor the transformer,
generator etc are rated in KVA. In heavy size transformer
copper loss is more and it vary with load and Climate i.e.
transformer oil condition but it is not main reason for
rating the transformer in KVA.

Pradyumna Chandra Panda
Berhampur Mob 9861357949