Difference Between Induction Motor and Synchronous Motor

Difference Between Induction Motor and Synchronous Motor

The motor used to convert electrical energy into mechanical energy. According to the power supply, the motors are classified as AC motor and DC motor.

The induction motor and synchronous motor are AC motors. The induction motor is a widely used motor in industries. The synchronous motor always runs on the synchronous speed. In this article, we will explain the difference between the induction motor and synchronous motor.

Before go through this article learn briefly about induction motor and synchronous motor.

Difference Between Induction Motor and Synchronous Motor

The difference between the induction motor and the synchronous motor is listed below.

Factor affecting motor Induction motor Synchronous motor
Supply system Three-phase AC supply is given to the stator winding of the motor. Three-phase AC supply is given to the stator winding and DC supply is given to the rotor winding.
Type of excitation It is a singly excited motor. It does not require DC supply for excitation. It is a doubly excited motor and it needs extra DC supply for excitation.
Working principle The induction motor works on the principle of electromagnetic induction. It works on the principle of exciting the rotor using DC supply and making it behaves as an electromagnet. It is made to lock with the synchronous speed of the magnetic field.
Rotor speed It rotates less than the speed of synchronous speed. It always rotates at the speed of synchronous speed.
Cost For the same rating, the cost of an induction motor is less than the synchronous motor. For the same rating, the cost of a synchronous motor is more than the induction motor.
Efficiency The efficiency of a motor is a little bit less than the efficiency of a synchronous motor. This type of motor has more efficiency.
Maintenance It requires less maintenance. It requires more maintenance.
Operation It is easy to operate. The operation of this motor is complex.
Effect of load If the load increases, the speed of the motor decreases. The speed will remains constant even if the load is changed.
Hunting When the load is suddenly changed, it will not experience hunting. It will experience hunting when the load is suddenly changed.
Construction The construction of this motor is very simple and robust. The construction of this motor is complex compared to the induction motor.
Starting It is a self-starting motor. It is not a self-starting motor. It has to run up to synchronous speed before it synchronized with AC supply.
Power factor It operates only at a lagging power factor. The power factor is very poor during a light load condition. It can operate either leading or lagging power factor. It can be changed by changing the excitation.
Application It is used where high starting torque is not required like;

  • Lathe machine,
  • Crane,
  • Hoist,
  • Pump,
  • Compressor,
  • Pressing machine, etc.
This type of motor is used where constant and precise speed is required like,

  • Clock,
  • Record player,
  • Ball mills,
  • Robot actuator, etc.

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