Transformer is a device that transfer electrical power from one circuit to another circuit without changing input power and frequency. Or one can say it can step up and step down the voltage while power and frequency remain constant.
Also there are two types of losses in transformer :-
- Copper losses
2. Iron losses or Core losses
In transformer Copper loss depend on current flowing through the winding of transformer, while Iron loss depend on Voltage which means total loss of transformer depends on voltage and current which is expressed in VoltAmpere VA and not on load Power factor (P.F.). So Transformer rating is expressed in VA or KVA and not in W or KW.