The damper winding (also known as ammortisseur) is mostly used in synchronous machine- in stator of synchronous generator and rotor of synchronous motor. It provides some specific advantage to synchronous machines like – smooth starting and compensating the transient effect or unbalanced condition.
The rotor of induction machine is mostly of squirrel cage type which is short circuited thus provides high current in start up.
Damper winding in synchronous machine is placed in the coil slots and short circuited. Thus Damper winding provides the same effect as the squirrel cage winding rotor does in case of induction motor.
Position of damper winding:
Damper winding is placed in the slots at the surface of pole shoes in salient pole machines and in in non-salient pole machine it is placed in the same slots with magnetizing windings.
Function of damper winding in synchronous machine:
2.Compensation of transients by damping the rotational fluctuation (hunting) caused by unbalanced loading, torque etc. Whenever the synchronous machine is pulled out from synchronism – as there will be relative motion between the rotor and stator, the damper winding will provide flux which will compensate the transient effect and machine will return back to synchronism.
Turbo Generator usually don’t have damper windings,as their solid field poles functions as damper.But they might use damper windings for synchronization purpose.