In actual practice, the rating of transformer is specified in:

Question

Question

This question was previously asked in

LPSC (ISRO) Technician B (Electronic Mechanic): Previous Year Paper (Held on 23 Feb 2020)

Answer 1

The losses in a transformer include copper losses and core losses or iron losses
Core losses depend on voltage whereas copper losses depend on the current which passes through transformer winding
The cu losses depend on the current rating of the load and the load type determines the power factor
The total losses depend on volt-ampere
So, the rating of the transformer is mentioned in kVA but not in kW

26 June 1

kW is Working Power also known as Actual Power or Active Power or Real Power. It is the power that powers the equipment and performs useful work.
Active power is measured by kW or MW meter.
KVAR is Reactive Power also known as watt less power. It is the power that magnetic equipment (transformer, motor, relay e.t.c.) needs to produce the magnetizing flux.
Reactive power is measured by kVAR or MVAR meter.
kVA is Apparent Power. It is the vectorial summation of kVAR and KW.
Apparent power is measured by kVA or MVA meter.