16 Main Difference between Synchronous Motor and Induction Motor

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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 an induction motor.

If you are doing preparation for the exam, viva or interview, you will be asked questions related to the synchronous and induction motor. 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 Motor [Tabular Format]

Let’s study the comparison between both AC motors (Synchronous and Induction Motor).

Sr. No Content Synchronous Motor Induction Motor
01 Definition The electromagnetic motor which converts electrical energy into mechanical work at constant speed is called as Synchronous Motor. The electromagnetic motor which converts electrical energy into mechanical work at variable speed is called as Induction Motor.
02 Motor Speed Synchronous motor runs at the synchronous speed. Induction motor runs at the non-synchronous speed.
03 Principle The synchronous motor works on the principle of the ‘Magnetic Locking‘. The induction motor works on the principle of ‘Electromagnetic Induction‘.
04 Starting Position It is a non-self starting motor. It is self- starting the motor. (especially three-phase induction motor)
05 Connected Supply

(AC and DC supply)

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.

06 Excitation 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.
07 Construction The construction of the synchronous motor is very difficult. The construction of the induction motor is relatively easy.
08 Relative Motion For 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.
09 Slip

(Difference between the speed of rotation of magnetic field and rotor speed)

Zero slip (S=0) occurs in the synchronous motor. The different slip occurs in the induction motor.

Motor Speed

(in r.p.m)

It runs at 150 to 1800 r.p.m. synchronous of speed. It runs at less than 1500 r.p.m. synchronous speed.
11 Power Factor It has unity or lagging or leading power factor.

Mostly it works on the unity power factor.

It has only lagging power factor.
12 Efficiency

(Ratio between power output and power 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.
13 Uses It is used for Power factor correction, constant speed load service, voltage regulation of transmission line, etc. It is mostly used in the industries.
14 Cost This motor is costlier than the induction motor. This motor is cheaper than the synchronous motor.
15 Maintainance Maximum maintenance is required. Minimum maintenance is required.
16 Example Fan, blowing fan, a dryer is an example of the synchronous motor. Conveyor belt, rolling mill, mixer, grinder are an example of the induction motor.

In the tubular form, I have covered most of the topics related to the difference between synchronous and induction motor. Hope this will help you for the preparation of the exam or interview.

Related Comparisons:

If you have any queries, drop me a message in the comment section below.

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