why transformer ratings in kva?

Answer Posted / saeid

Watt is unite of work in physics.
When anything does some work, it will be described or
measured by KW. Then one of its specification is
KW . In oder words, KW is used for whatever equipment or
machine that does work. For example,generator, motor,
heater or a lump do work and they are identifying by KW. On
the other hand, a transformer doesn't
do any work. It only convert voltage and current while its
input energy is almost equal to its out put energy. In
fact, It’s not considered a source of power or a load for
power system. As a result, we use KVA to identify capacity
of a transformer instead of KW that can not be used
technicaly.
Additionally, I do not believe that this discussion is
related to power factor, copper loss or core loss of the
transformer.

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