What is "amortisseur winding"

n. A squirrel cage winding placed near the surface of the pole faces of a synchronous motor. Its main purpose is to dampen any speed fluctuations or oscillations that may occur as a result of sudden load changes. It is also used to accelerate the motor during starting. All the windings are shorted at the two ends of each pole of the motor. As the rotating field moves past the winding it induces currents in the winding which produce torque and accelerate the motor so as to overcome the lag in its speed.