why transformer are rated in KVA not in watt?

Answer Posted / syed qamar abbas

There are two types of losses in transformer. One is
variable type i.e. copper loss which depends on load
current since load current is of variable nature thats why
it is called varialbe losses and the other is fixed or
constant losses i.e iron loss which depends on voltage and
frequency,since both voltage and frequency is fixed that is
why it is called constant or fixed type of losses. These
two types of losses are not affected by the power factor.
This is why transformers are rated in KVA and not KW

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