Reasons why transformers are rated in KVA
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| Transformer |
It is important to know what is a transformer.
A transformer is a static device which converts electrical energy from one voltage level to another at the same frequency.
Transformers are rated in KVA not in KVAR nor in KW because of the following reasons:
- KVA=Kilo Volt X Ampere meanwhile KW=Kilo Volt X Ampere X Power factor since transformers are rated based on the maximum amount of power they can transfer, we see that the apparent power in transformers ( total power= active power+reactive power) is independent of the power factor.
- A transformer is not a load but only transfers energy from the primary to the secondary at same power and the iron loss and cu loss in transformers are independent of the power factor. The power factor is only associated with loads which may be:
- Inductive- lagging pf
- Capacitive-leading pf
- Resistive (unity power factor)
Examples are motors