Why Transformer Rating is Expressed in kVA and not kW

Transformers are rated in kVA (kilovolt-ampere) and not in kW (kilowatt) because the total losses in a transformer depend upon volt-ampere (VA) only and not on the power factor of the load1345. The losses in a transformer are due to voltage and current, and not to power factor35. Thus, the rating of the transformer is done in kVA, not in kW12345.A transformer only transfers the power from one circuit to another without changing the value of power and frequency2. It can only step up or step down the value of current and voltage while the power and frequency remain the same2. The nameplate of a transformer provides general data, such as rating in VA, single phase/three phase, power or distribution transformer, and impedance voltage2.In summary, transformers are rated in kVA and not in kW because the losses occurring in the transformers are independent of power factor4. The rating of a transformer is done in VA, and the losses in a transformer are due to voltage and current, not to power factor1345.