In a typical motor starter configuration, the protective device included to guard the motor in case of overload is a ______.

• A. Circuit breaker
• B. Overvoltage protector
• C. Thermal overload
• D. Fuse

Answer: (C)

Motor overload protection in a typical starter is provided by a thermal overload device. This component is designed to sense the windings’ temperature as the motor runs, especially under overload or stall conditions. When the winding temperature rises beyond its safe limit, the thermal overload trips and opens the circuit to the motor, protecting the insulation and windings from damage. It’s integrated into the starter assembly so protection is coordinated with the motor current load and is reset after cooling.

Fuses and circuit breakers respond to high current, but they don’t monitor winding temperature in the same way and may not protect the motor from gradual overheating. An overvoltage protector guards against voltage spikes rather than protecting against overheating due to overcurrent. Therefore, the device specifically suited to guard the motor from overheating is the thermal overload.