When a motor's starter coil energizes but the motor does not start, which issue is most likely?

When a motor's starter coil energizes but the motor does not start, which issue is most likely?

• A. Inadequate line voltage
• B. Open motor winding
• C. Faulty overload
• D. Stuck mechanical load

Answer: (A)

When the starter coil energizes but the motor doesn’t start, the most likely issue is that the supply voltage at the motor is too low to develop the starting torque needed to overcome inertia. Under-voltage reduces the current in the windings, so the motor can’t produce enough torque to accelerate, often just humming instead of turning. If a winding were open, the coil wouldn’t energize properly and you’d see no magnetic field at all. A faulty overload typically trips and cuts power, so the starter coil wouldn’t remain energized. A stuck mechanical load can cause the motor to attempt to start and stall, but the immediate symptom of energizing the coil without rotation is most commonly under-voltage.

When the starter coil energizes but the motor doesn’t start, the most likely issue is that the supply voltage at the motor is too low to develop the starting torque needed to overcome inertia. Under-voltage reduces the current in the windings, so the motor can’t produce enough torque to accelerate, often just humming instead of turning.

If a winding were open, the coil wouldn’t energize properly and you’d see no magnetic field at all. A faulty overload typically trips and cuts power, so the starter coil wouldn’t remain energized. A stuck mechanical load can cause the motor to attempt to start and stall, but the immediate symptom of energizing the coil without rotation is most commonly under-voltage.