Transformers are rated using—

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Multiple Choice

Transformers are rated using—

Explanation:
The main idea is that transformers are sized by apparent power, measured in volt-amperes. This rating reflects the combination of voltage and current the windings can carry safely without overheating. The reason volts times amps is used instead of watts is that the current that causes heating depends on the current itself, not just the real power delivered to a load. Real power (watts) varies with the load’s power factor, whereas the transformer must be able to handle worst-case current across all pf values. So the VA rating stays consistent for different loads, ensuring the transformer won’t overheat. Ohms and henries describe resistance and inductance, not the overall capacity to transfer power, and watts alone can mislead because they don’t account for power factor.

The main idea is that transformers are sized by apparent power, measured in volt-amperes. This rating reflects the combination of voltage and current the windings can carry safely without overheating. The reason volts times amps is used instead of watts is that the current that causes heating depends on the current itself, not just the real power delivered to a load. Real power (watts) varies with the load’s power factor, whereas the transformer must be able to handle worst-case current across all pf values. So the VA rating stays consistent for different loads, ensuring the transformer won’t overheat. Ohms and henries describe resistance and inductance, not the overall capacity to transfer power, and watts alone can mislead because they don’t account for power factor.

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