Difference between Induction Motor and Synchronous Motor

Three-phase induction motor also called an asynchronous motor is a widely used induction motor in the industry because it is cheaper, robust, efficient, and reliable. we are going to discuss the difference between Induction Motor and Synchronous Motor in this post.

On the other hand, a synchronous motor is mostly used in constant speed applications as it operates at synchronous speed as the name suggests. The synchronous machine can operate as a generator as well as a motor.

Comparison between synchronous motor and induction motor

Synchronous MotorInduction Motor
1) Synchronous motor is a doubly excited machine. its armature winding is excited by ac source and field winding by a dc source.1) An three-phase induction machine is a singly excited machine. its starter is fed with ac source.
2) It is the constant-speed motor and synchronous motor speed is independent of the load2) It always operates at a speed less than synchronous speed and its speed decreases as the load increases.
3) Synchronous motor is not self-starting. it has to be run up to synchronous speed by some means before it can be synchronized to an ac source.3) Three phase induction motor is self-starting
4) Synchronous motor can be operated at both lagging and leading power factor by varying excitation.4) induction motor can be only operated at a lagging power factor.
5) It can be used as a synchronous condenser to improve the power factor of the power system.5) Induction motor is used only to drive mechanical loads in industry and in commercial use.
6) Synchronous motor efficiency is more compared to three-phase induction motor.6) Efficiency is less compared to the synchronous motor
7) It is costlier than the induction motor7) It is cheaper than a synchronous motor
8) Starting torque is more compared to induction motor8) Starting torque is less than the synchronous motor

The major differences

  1. the synchronous motor always rotates at a synchronous speed whereas an induction motor never rotates at a synchronous speed speed always remains less than synchronous speed.
  2. The synchronous motor is not self-starting on other hand three phase induction motor is self starting.
  3. Synchronous motor can operate on lagging and leading power factor whereas induction motor only run at lagging power factor.
  4. it is called a synchronous motor because it run at synchronous speed whereas inuction motor also called as asynchronous motor


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