Amortisseur windings in a synchronous motor help start by temporarily behaving like an induction motor before reaching synchronous speed.

• A. True
• B. False
• C. Not applicable
• D. Sometimes

Answer: (A)

Damper windings, also known as damper or amortisseur windings, provide starting torque by acting like an induction motor temporarily. They are shorted-turn conductors embedded in the rotor that form a miniature cage. When the stator is energized, the rotating magnetic field induces currents in these windings. Because the turns are shorted, those currents produce a rotor torque similar to an induction motor, allowing the rotor to accelerate even though it hasn’t reached synchronous speed yet. This starting action also helps dampen speed oscillations as the machine accelerates toward lock-in.

As the rotor speeds up, the slip between the rotor and the rotating field decreases, so the induced currents and the induction-like torque diminish. When the rotor nears synchronous speed and the DC field is appropriately excited, the rotor locks into step with the stator field, and the machine shifts from starting torque provided by the damper windings to steady synchronous operation. If damper windings were absent, starting the motor would require a separate method to get it up to speed, which is why their presence makes starting feasible.