Answer / amr mobarak

From the Theory of Design of any transformer we know that :-

S(primary ) = S(secondary ) , neglecting the Losses
I.V (primary ) = I.V (secondary )

So When We Try to Describe any Transformer We Refer to VA or
KVA or MVA as their Values are the Key of Design not The
Power ( Active or Reactive ).

Answer / reema

actually rating of a equipment depends upon heat , which
depends upon loss. as in transformer both copper loss &iron
loss dont depend upon power factor . so transformer rating
is in kva.

Answer / geno peter

well, the transformer is independent of the load power
factor thats why KVA

In design we take UPF

Answer / yasir

Both the losses copper loss(depends on current) and iron
loss(depends on voltage) are independent of power factor,
that is why a Transformers rating is not on kW, but on KVA.

Answer / waqar joyo

its because power factor of the load is not constant ...
load is not constant continously varies dats y itz in kva
instead of kw

Answer / anathal

Copper loss of a transformer depends on current and iron
loss on voltage . Hence total losses depends on Volt-
Ampere and not on the power factor. That is why the rating
of transformers are in kVA and not in kW.

http://electricalinterviewquestion.blogspot.com/2010/08/why-
transformers-are-rated-in-kva.html

Answer / saran

normally rating of a equipment depends upon heat , which
depends upon loss. as in transformer both copper loss &iron
loss dont depend upon power factor . so transformer rating
is in kva.

Answer / r.jayaraj

because,ironloss is depends in voltage and cu_loss is
depends in current.so the transformer ratings in kva

Answer / kb shrinivasa

Since transformer is a static there will not be any
rotational losses it have only iron loss depend upon
voltage and copper loss depend upon current

for AC supply systems like generator, transformer rating is
done in KVA because of inductance present in AC . we don't
know load is resitive or inductive

it is independent there fore it is measured in kva

Answer / vijay

In transformer cu loss depends on I, iron loss depends on V,
So, total t/f loss depend on VA, Not on the phase angle bt V
&I. That is independent of load power factor that is y the
t/f is rated in KVA rather than KW

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