Which outcome arises when a power transformer experiences prolonged operation above its rated kVA with inadequate cooling?

💡 Explanation

When a transformer operates above its rated kVA with insufficient cooling, increased current flow causes ohmic heating in the windings because of I^2R losses, leading to high temperatures that degrade the insulation. Consequently accelerated insulation breakdown occurs, rather than resonance, harmonic distortion, or voltage sag which involves different electrical phenomena.

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