Question 181Electricity & Electronics - 1st Asst/Chief

The correct answer is C) an open overload "OL" heater. When the motor fails to start and gives a loud hum, it indicates that the motor is not receiving enough current to start. This is most likely due to an issue with the overload "OL" heater, which is responsible for protecting the motor from overcurrent conditions. If the overload heater is open, it will prevent the necessary current from reaching the motor, causing the observed symptoms. The other answer choices are incorrect because an open main contactor "M" coil (A) would prevent the motor from starting entirely, an open overload "OL" relay contact (B) would also prevent the motor from starting, and an open disconnect switch "DS" (D) would disconnect power to the entire circuit, not just the motor.