Difference between Synchronous and Induction Motor

Synchronous Motor:

A Synchronous motor same relationship to an alternator as a Dc motor If the alternator supplying the AC power to run the motor to doing mechanical work .If the mechanical work apply on rotating alternator. It removed remaining DC power and supply the AC power to the armature terminal the torque will be developed and alternator running continuetly . We find the speed of motor by the AC supply frequency and number of poles on the synchronous machine. 

The poly-phase synchronous motor same as a alternator. The essential parts of a three phase synchronous motor are:

1. Lamination stator core with three phase armature winding

2. Rotating field structure complete with damper winding and slip rings.

3. Brushes and brush holder.

4. Two end shields to house the bearing that support the rotate shaft. 

Stator core and winding most commonly as three- phase alternator The leads from the stator winding terminate in terminal box. The salient field poles connected to give alternate polarity. The number of rotor field poles same as stator field poles. The field circuit leads two slip rings mounted on the shaft and carbon brushes mounted in brush holders make connected with a two slip ring.

Induction Motor:

The induction motor is the used as a AC motor. Induction motor low in cost, simple extremely rugged construction, high reliability, high efficiency, reasonably good power factor low maintenance cost and simple starting arrangements. It differs from other types of electric motors in that there is no electrical connection from the rotor ending to any source of supply. The necessary current and voltage in the rotor circuit are produced by induction from the stator winding. This is the reason that it is called the induction motor.

The induction motor consists of two parts 

1. Stationary part known as stator

2.The revolving part, known as the rotor. Induction motor are depending on three type of rotor. 

1.Squirrel cage rotor 

2.Wound rotor or slip ring 

3.Double squirrel cage rotor. All induction motor working on same principle. 

Comparison Between Synchronous and induction motors:

S. no	INDUCTION MOTOR	SYNCHROUNOUS MOTOR
1	It has got no self starting torque and some external means is required for its starting.	No special means is required for starting But It has got self starting torque.
2	Average speed is constant and independent on load.	Its speed falls with the increase in load and always less than synchronous motor.
3	It can be operated under a wide range of power factor depend on lagging or leading.	It operates only lagging power factor not on depend on leading power factor .which becomes poor at lights loads.
4	It required DC excitation So it is a Doubly excited machine.	It required no DC excitation So it is a singly excited machine

This is all about difference between induction motor and synchrounous motor.