Question 311Electricity & Electronics - Assistant Engineer

The correct answer is C) Higher than normal operating temperature. Higher than normal operating temperature of an electric motor can indicate the need to clean the insulation on the windings. This is because dirty or contaminated windings can lead to increased resistance, which in turn causes the motor to run hotter than normal. Cleaning the insulation helps restore proper heat dissipation and allows the motor to operate at its designed temperature. The other options are not direct indicators of the need to clean the motor windings. Excessive vibration (A) could have other causes, sparking at the brushes (B) may indicate brush or commutator issues, and high megger readings (D) would suggest the insulation is in good condition, not requiring cleaning.