Synchronous Motor Speed: Starting from its name […]
Speed: Starting from its name ‘synchronous’, this motor runs at synchronous speed whatever the amount of load it may be. The speed of this kind of motor is not dependent on the load.
Starting Torque: This motor does not have any self starting torque, so some other auxiliary means have to be provided for starting the synchronous machine.
Excitation: Synchronous motor is a doubly excited machine. The field winding that is rotor is excited using DC source and its stator that is armature winding is excited using AC source. In addition to that it can be made to operate at leading power factor from lagging power factor just by changing its excitation.
Cost: This kind of motor is much costlier that a similar rating induction motor.
Speed: The speed of induction motor is always less than the synchronous speed and it is dependent on the load since the speed decreases with the increase in load.
Starting Torque: This kind of motor has its own self starting torque.
Excitation: It is a singly excited machine where its stator windings are excited using an AC source. Contrary to the case of synchronous motor, induction motor works only under lagging power factor.
Cost: The cost of induction machine is less when compared with a synchronous motor of same rating.
All these comparisons show that synchronous motors are more efficient than induction motors.