16 Main Difference between Synchronous and Induction Motors

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In this post, we are learning the difference between the two types of alternating currents (AC) motor. These two AC motors are-

  • Synchronous motor and
  • Induction motor.

If you are doing preparation for the exam, viva, or interview, you will be asked questions- synchronous vs induction motors. These are very important topics in electrical engineering.

Many times you will be asked to compare these two types of motors.

Here, I’m comparing synchronous motor and asynchronous motor with their specifications, functions, applications, and examples.

Note: Induction motor is called the ‘Asynchronous Motor‘.

Difference between Synchronous and Induction Motors

Let’s study the comparison between both AC motors in tabular form.

#ContentSynchronous MotorInduction Motor
01Definition
[What is a synchronous & Induction motors]
The electromagnetic motor which converts electrical energy into mechanical work at constant speed is called as a ‘Synchronous Motor’.The electromagnetic motor which converts electrical energy into mechanical work at variable speed is called as a ‘Induction Motor’.
02Motor SpeedSynchronous motor runs at the synchronous speed.Induction motor runs at the non-synchronous speed.
03PrincipleThe synchronous motor works on the principle of the ‘Magnetic Locking’.The induction motor works on the principle of ‘Electromagnetic Induction’.
04Starting PositionIt is a non-self starting motor.It is self-starting the motor. (especially three-phase induction motor)
05Connected Supply  
(AC and DC)
It consists of two main parts- the stator and rotor.  

Stator connects with the three-phase AC supply and Rotor connects with the DC supply respectively.
Similarly, it also consists of two main parts- the stator and rotor.

The only Stator connects with the three-phase AC supply.
06Excitation System   (DC source for rotor)The synchronous motor requires the DC excitation system (or prime mover) to start the motor (i.e. for the rotor rotating).The induction motor does not require an excitation system to start the motor.
07ConstructionThe construction of the synchronous motor is very difficult.The construction of the induction motor is relatively easy.
08Relative MotionFor Synchronous motor, relative motion is not required in between the stator and rotor.For Induction motor, relative motion is required in between the stator and rotor.
09Slip
(magnetic field vs rotor speed)
Zero slip (S=0) occurs in the synchronous motor.The different slip occurs in the induction motor.
10Motor Speed
(in r.p.m)
It runs from 150 to 1800 rpm. synchronous of speed.It runs at less than 1500 rpm. synchronous speed.
11Power FactorIt has unity or lagging or leading power factor.  
Mostly it works on the unity power factor.
It has only a lagging power factor.
12Efficiency  
(Ratio of power output & input)
The synchronous motor has more power efficiency due to the unity or leading power factor.The induction motor is less efficient than the synchronous motor.
13UsesIt is used for power factor correction, constant speed load service, voltage regulation of transmission line, etc.It is mostly used in the industries.
14CostThis motor is costlier than the induction motor.This motor is cheaper than the synchronous motor.
15MaintainanceMaximum maintenance is required.Minimum maintenance is required.
16ExampleFan, blowing fan, a dryer is an example of the synchronous motor.Conveyor belt, rolling mill, mixer, grinder are an example of the induction motor.

This is all about the difference between synchronous and induction motors. Also covered the advantages and disadvantages of these two AC motors.

Hope this will help you for the preparation of the exam or interview. If you have any queries, drop me a message in the comment section below.

Related some comparisons:

Thanks for Reading!

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