The phenomenon of oscillation of the rotor about its equilibrium position is called ________.

The damper winding in a synchronous motor performs two functions:

• Prevents hunting (damped out oscillations)
• Provides starting torque (made self-starting)

Under normal running conditions, damper winding does not carry any current.

Hunting is a phenomenon that occurs in synchronous motors due to varying load or supply frequency.

Causes of hunting:

• Periodic variation of load (oscillation of the rotor)
• Sudden changes in load
• Faults occurring in the system when supplied by the generator
• Sudden change in the field current
• Cyclic variations of the load torque

Effects of hunting:

• It can lead to loss of synchronism
• It can cause variations of the supply voltage producing undesirable lamp flicker
• The possibility of resonance condition increases. If the frequency of the torque component becomes equal to that of the transient oscillations of the synchronous machine, resonance may take place
• Large mechanical stresses may develop in the rotor shaft
• The machine losses increases and the temperature of the machine rises