Why does transformer rating in kva

But the alternator and the transformer are the only machines which are rated in volt-amp VA. The machines which consumed power are rated in KW. But the main work of transformer is to transmit the power and not to consume the power, i. There are two reasons because of which the rating of the transformer is in kVA. Let understand this in details.

The above equations show that the power factor is the only terms which make the difference between the two. To take it a step further, if you have an ability to cool the transformer further, you can augment the kVA or MVA rating of a transformer. If you think of it, this is not different from a cable or a conductor's capacity expression. Except that a transformer can have more than one voltage levels and different ampacities on primary and secondary, but the kVA rating remains the same on either side.

So that makes kVA a more convenient way to express its thermal capacity vs. How is Vector Control improving motor output torque capability?

How to select the right cable? KVA is the unit of apparent power. It is a combination of real power and reactive power. Transformers are manufactured without considering the load being connected. So any kind of electrical load can be connected to it either resistive, capacitive, inductive or combination loads. If the transformer is rated in KW, there may be confusions regarding the type of load being connected. This is why the transformer is rated in KVA. By doing so we can eliminate the confusions regarding the type of load being connected.

Another important thing Emmanuel is We step up voltages so that we have low current since they are inversly proportion remember ohms law. You know what you can wornder the current in transmission can be almost 20 amp. To balance the loss of voltage while transferring and receiving the input. Also, the power factor depends upon the load.

In actual practice, the pure inductive lagging and pure capacitive leading loads do not exist, i. Hence, the practical loads draw both active and reactive powers from the supply. For example, an induction motor has windings which are inductive and also possess some resistance.