Damper winding in synchronous motors is used to ________.

A) Prevent the effect of hunting

B) Make synchronous motors self-starting

C) Reduce the speed of synchronous motors

D) Provide constant synchronous motor torque

Starting methods of Synchronous motor

A synchronous motor is not a self-starting motor. It is stated in the following ways:

1.) Using an Auxiliary Motor

• A small auxiliary motor (often an induction motor) is used to bring the synchronous motor up to near synchronous speed. Once the synchronous motor reaches a speed close to its synchronous speed, the DC field is excited, and the synchronous motor locks in with the supply frequency.
   

2.) Damper Winding

• The synchronous motor is equipped with additional squirrel-cage windings, known as damper windings, embedded in the pole faces of the rotor. Initially, the motor starts as an induction motor using the damper winding. As the rotor accelerates and approaches synchronous speed, the main DC excitation is applied to the rotor field winding, and the motor synchronizes with the supply frequency.
• Damper windings are indeed useful in reducing or preventing hunting (oscillations) in alternators. They provide additional damping and stabilize the machine's operation by dissipating the oscillatory energy.
• Under normal operating conditions, when the alternator is running at synchronous speed, the damper windings do not carry significant currents. They only become active during transient conditions or when the alternator is not synchronized.
• Damper windings are used to provide starting torque. They are also used to dampen oscillations and stabilize the machine. Starting torque is not a role of damper windings; it's more related to the operation of induction motors.

Additional Information 

Hunting in synchronous motor:

• Hunting is the phenomenon of a synchronous motor's rotor oscillating around its equilibrium position or steady state, when there's a sudden change in load. This can cause the motor's speed to fluctuate momentarily.
• Hunting can be caused by several factors, including Sudden changes in load, Periodic variation of load, Faults in the generator-supplied system, Sudden changes in field current, and Cyclic variations of the load torque.