Why Transformer Rating in KVA not in KW

Transformer Rating in KVA not in KW: 

As We know Two type of losses in Transformers:-

1. Cu Loss  (Copper Loss)
2. Iron Loss

Cu loss of transformer depends on Current and Iron Loss of Transformer Depends on Voltage. So, Total Transformer loss depends on Voltage-Ampere and not on phase angle between voltage and current i.e. it is independent of total power factor (pf).

For that kind of reason Transformer Rating is in KVA ( Kilo Volt Ampere ) and not in KW (kilo watt).