What might indicate a bad transformer during testing?

Unusual heat generation during testing is a strong indicator of a bad transformer. Transformers are designed to operate within specific temperature ranges; excessive heat can suggest overload, winding short circuits, or insulation failure. When a transformer overheats, it can lead to circuit damage, and ultimately, failure of the unit. The presence of hot spots can signify electrical shorts or other issues that compromise the transformer's integrity, making careful monitoring of temperature critical during testing.

In contrast, standard operational noise is expected in well-functioning transformers, as they typically emit sounds due to magnetostriction in the core or movement of parts. Even voltage readings suggest that the transformer is functioning properly, as a transformer's ability to maintain voltage without significant fluctuation is essential for its role in electrical systems. Stable temperature indicates that the transformer is not experiencing overheating or failure, confirming it operates correctly.