Q4Electrical Machine Design
Question
Q.4. Explain the use of damper winding in synchronous machine.
Answer
Damper winding in a synchronous machine damps hunting oscillations, provides starting torque for synchronous motors, and reduces negative-sequence effects from unbalanced loading.
Damper winding in a synchronous machine is used to damp hunting (rotor speed oscillations following load disturbances) by inducing currents in the short-circuited damper bars whenever the rotor deviates from exact synchronous speed, producing a torque that opposes and damps the oscillation; to provide starting torque for synchronous motors (which have no inherent starting torque from the DC field alone), allowing the motor to start as an induction motor using the damper cage before field excitation is applied; and to reduce the effects of unbalanced armature currents (negative-sequence currents) by providing a low-impedance path that limits the resulting rotor surface heating and torque pulsations.