Damper windings

[رضوى أحمد]

السلام عليكم ورحمة الله وبركاته....
أريد من سيادتكم تبسيط فكرة عمل Damper windings في الالات المتزامنة....
شكراً

[محمد صلاح]

وعليكم السلام ورحمة الله وبركاته
synchchronous motors are not self starting so there are two methods for starting:
first : starting using variable frequncy supply
second: strating as induction motors

damper winding is used for starting synchronous motors as induction motors which resembles the cage of an induction motor.
to start the syncgronous motor the field winding is left unexcited ,when the motor terminals are now connected to the ac supply the motor will start as induction motor because currents will be induced in the dumper winding , the motor will speed up and will approach to synchronous speed .
now if the rotor poles are excited from a dc source the rotor will then run at synchronous speed .
if the machine runs at synchronous speed no current will be induced in the damper winding.
Although dumper winding is not required to start synchronous generator , both synchronous generators and motors have dumper windings to damp out transient oscillation as currents will be induced in it to produce a torque to restore the synchronous speed.