What is a standard method to troubleshoot a transformer?

• A. Measuring the surface temperature
• B. Testing insulation resistance
• C. Measuring the continuity of the coils
• D. Measuring the input voltage

Answer: (C)

Verifying that each winding is a closed circuit is the standard first step in transformer troubleshooting. Measuring the continuity of the coils confirms there is an uninterrupted path through the windings and that the windings are retained in good condition without open circuits or broken conductors. If a winding has an open circuit, the transformer cannot transfer power properly, and the fault is basically isolated to that winding, making the problem quick to pinpoint.

Other checks have value for understanding symptoms or broader health, but they don’t directly diagnose the most common fault you’d encounter first. Checking surface temperature can show overheating, which is a symptom rather than a direct indication of winding integrity. Testing insulation resistance assesses insulation quality, which is important for long-term reliability but doesn’t prove the coil itself is continuous. Measuring the input voltage confirms what the supply is delivering, not the internal state of the windings.