What is the difference between induction machine and synchronous machine?

1.Induction machine is a self starting machine and synchronous machine is not self starting machine 2.Induction machine rotor rotate bolew synchronous speed and synchronous machine rotor rotate synchronous speed

Synchronous Motor:

1.                   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.

2.                   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.

3.                   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.

4.                   Efficiency:  This is comparatively more efficient than induction            motor.

 

5.                   Cost: This kind of motor is much costlier that a similar rating

 

induction motor.

 

1.                   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.

2.                   Starting Torque: This kind of motor has its own self-starting torque.

3.                   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.

4.                   Efficiency: It is comparatively less efficient.

 

5.                   Cost: The cost of induction machine is less when compared with a synchronous motor of same rating.

Synchronous machines run at constant speed but the induction machine can operate at different speeds.

Thanks for invitation..I know some different between those.. *Synchronous motors require an additional DC power source for energizing rotor winding. Induction motors do not require any additional power source. *Slip rings and brushes are required in synchronous motors, but not in Induction motors (except wound type induction motor in which slip ring motors are used to add external resistance to the rotor winding). *Synchronous motors require additional starting mechanism to initially rotate the rotor near to the synchronous speed. No starting mechanism is required in induction motors. *The power factor of a synchronous motor can be adjusted to lagging, unity or leading by varying the excitation, whereas, an induction motor always runs at lagging power factor. *Synchronous motors are generally more efficient than induction motors. *Synchronous motors are costlier. Best Regards

induction machine can't run at synchronous speed it always low little bit ,contain only one source of electric required for motion

while synchronous one rotates at synchronous speed contain of DC source at rotor and ac at stator to start rotation