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Synchronous motor |
Induction motor |
| It is a type of AC motor, in which the rotor will rotate synchronously with the rotating magnetic field produced by the supply and that’s why it is called as synchronous motor. | It is a type of AC motor in which the rotor will always rotate less than the synchronous speed and that’s why induction motor is called as a asynchronous motor. |
| A synchronous motor is a doubly excited machine. | A synchronous motor is a doubly excited machine. |
| An AC source energized its armature winding and a DC source energized its field winding. | An AC source energized its stator winding. |
| The speed of the motor is independent of the load. | The speed of the induction motor is inversely proportional to the load. |
| Synchronous motor works on the principle of magnetic locking. | Induction motor works on the principle of electromagnetic induction. |
| Synchronous motor are not self starting and the method used for stating synchronous motor are using a pony motor, damper windings, used as a slip ring induction motor. | 3 phase induction motors are self starting but Single phase induction motors are not self starting. Induction motor has self starting torque. |
| By changing its excitation,this motor can operate with leading and lagging power factor | At high loads the power factor becomes very poor hence induction motor can operates only at a lagging power factor. |
| Its efficiency is more than induction motor of the same output and voltage rating. | Its efficiency is less than synchronous motor of the same output and voltage rating. |
| Synchronous motor is more expensive than that of induction motor. | Induction motor is cheaper than that of synchronous motor. |
| There are two types of rotor in synchronous motor and they are salient pole rotor and non-salient pole rotor. | There are also two types of rotor in induction motor and they are squirrel cage rotor and slip ring or wound rotor or phase wound rotor |
| Synchronous motor is used for the improvement of power factor of transmission line. It is the heart of power system. They are also used in ball mills, watches, record players and turntables. | Almost 90% of industry machines are induction motors, they are used in electric fan, blowers, centrifugal pumps, compressors, conveyors, punch presses and bulldozers etc. |
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