How are transformers rated?

Transformers are rated in Volt-Amperes (VA) because this measurement reflects the apparent power that they can handle. The VA rating combines both the voltage and current that the transformer can deliver without overheating or becoming overloaded. This is particularly important for applications where the transformer must provide power to devices with varying power factors, as the transformer will need to account for both real power (measured in watts) and reactive power.

Choosing Volt-Amperes as the rating allows for a more comprehensive understanding of how a transformer will perform in practical applications. It provides a clear indication of how much electrical load can be safely connected to the transformer while ensuring safe and efficient operation. Other units of measurement, such as watts or volts, do not account for the reactive power that may be present in AC circuits, thus making Volt-Amperes the most appropriate rating for transformers.