What measurement unit is used to rate transformers?

Transformers are rated in volt-amperes (VA) because this unit takes into account both the voltage and the current within the circuit, providing a measurement of apparent power. Since transformers can operate with inductive or resistive loads and do not have a fixed power factor, VA is a more appropriate measure than kilowatts (KW).

When transformers are rated with VA at the secondary side, it reflects the maximum load they can supply without overloading, which is crucial for ensuring safe and efficient operation. This means that the transformers can deliver power to various devices while accounting for the characteristics of the electrical load they are supplying.

Using VA helps in assessing the transformer’s capacity irrespective of any power factor associated with the loads connected to it. Therefore, referring to the rating in VA at the secondary position is the most accurate and commonly accepted method in the electrical field.