Michelin ECT Full Course Practice Exam

In an induction motor, the rotor never reaches synchronous speed; it runs a little slower, with slip defined as the percentage difference between synchronous speed and rotor speed. The observed pattern—very small slip at no load and only a modest 3–5% slip under full load—shows that the rotor speed stays very close to synchronous speed across different loads. That means the motor maintains nearly the same operating speed despite changing load, which is the defining trait of a constant speed motor.

If speed were meant to vary significantly with load, you’d expect larger shifts in slip or explicit speed-control mechanisms. The starting torque concern or efficiency alone doesn’t explain this behavior.

So the motor’s behavior indicates a constant speed motor.