Red Seal Electrician Practice
MotorsQuestion 1210 of 1506

A synchronous motor suddenly gets a load much larger than its maximum torque. What happens?

  1. The rotor speeds up above synchronous speed to carry the load.
  2. The motor keeps its speed and only draws more current.
  3. The motor slips a few percent, like an induction motor.
  4. The rotor falls out of step with the field, and the motor loses its torque.
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Correct answer: The rotor falls out of step with the field, and the motor loses its torque.

Torque exists only while the rotor stays synchronized. Too much load breaks the lock.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 13.2: Synchronous Motors

Practice motors

Questions last reviewed: 18 October 2026