Types of Induction Motors

What are The Types of Induction Motors?

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There are basically two types of induction motor that depend upon the input supply – single phase induction motor and three phase induction motor. Single phase induction motor is not a self starting motor which we will discuss later and three phase induction motor is a self-starting motor.

There are mainly two types of induction motor on the basis of power supply, Single Phase Induction Motor and Three Phase Induction Motor. As their name suggests, 1 phase AC power supply is extended to single phase induction motor while three phase induction motor is connected to 3 phase AC power supply.

What are The Types of Induction Motors?

By far, the most common type of three phase motor is the squirrel cage  motor, but there are also wound rotor motors (also called slipring  motors). Squirrel cage motors have different torque vs. speed design  types. In the USA, the standard designs are designated A, B, C and D  with design B being the most common. There are also various enclosure  designs and mounting arrangements.

Single phase motors have various starting arrangements. Capacitor start  motors are probably the most common. There are also permanent split  capacitor motors, shaded pole motors and others.

Types of Single Phase Induction Motor

We can easily conclude that the single-phase induction motors are not self-starting because the produced stator flux is alternating in nature and at the starting, the two components of this flux cancel each other and hence there is no net torque.

The solution to this problem is that if we make the stator flux rotating type, rather than alternating type, which rotates in one particular direction only. Then the induction motor will become self-starting. Now for producing this rotating magnetic field, we require two alternating flux, having some phase difference angle between them.

When these two fluxes interact with each other, they will produce a resultant flux. This resultant flux is rotating in nature and rotates in space in one particular direction only. Once the motor starts running, we can remove the additional flux.

The motor will continue to run under the influence of the main flux only. Depending upon the methods for making asynchronous motor as Self Starting Motor, there are mainly four types of single phase induction motor namely:

  1. Split phase induction motor,
  2. Capacitor start inductor motor,
  3. Capacitor start capacitor run induction motor,
  4. Shaded pole induction motor.
  5. Permanent split capacitor motor or single value capacitor motor.

Types of Three Phase Induction Motor

Induction motor is also called asynchronous motor as it runs at a speed other than the synchronous speed. Like any other electrical motor, induction motor have two main parts namely rotor and stator.

Stator

As the name indicates stator is a stationary part of induction motor. A three phase supply is given to the stator of the induction motor.

Rotor

The rotor is a rotating part of induction motor. The rotor is connected to the mechanical load through the shaft. The rotors of the three phase induction motor are further classified as:

  1. Squirrel Cage Rotor,
  2. Slip Ring Rotor or Wound Rotor or Phase Wound Rotor.

Depending upon the type of rotor used the three-phase induction motor is classified as:

  1. Squirrel Cage Induction Motor
  2. Slip Ring Induction Motor or Wound Rotor Induction Motor or Phase Wound Induction Motor.

The construction of stator for both the kind of three phase induction motor remains the same and is discussed in brief in next paragraph.

Stator of Three Phase Induction Motor

The stator of the three phase induction motor consists of three main parts:

  1. Stator frame
  2. Stator core
  3. Stator winding or field winding

Stator Frame

It is the outer part of the three-phase induction motor. Its main function is to support the stator core and the field winding. It acts as a covering and provides protection and mechanical strength to all the inner parts of the machine.

The frame is either made up of die-cast or fabricated steel. The frame of three phase induction motor should be strong and rigid as the air gap length of three phase induction motor is very small. Otherwise, rotor will not remain concentric with stator which will give rise to unbalanced magnetic pull.

Stator Core

The main function of the stator core is to carry alternating flux. In order to reduce the eddy current losses the stator core is laminated. This laminated type of structure is made up of stamping which is about 0.4 to 0.5 mm thick. All the stamping are stamped together to form stator core, which is then housed in stator frame. The stampings are generally made up of silicon steel, which reduces the hysteresis loss.

Stator Winding or Field Winding

The slots on the periphery of stator core of the three phase induction motor carries three phase windings. This three phase winding is supplied by three phase ac supply. The three phases of the winding are connected either in star or delta depending upon which type of starting method is used.

The squirrel cage motor is mostly started by star-delta stater and hence the stator of squirrel cage motor are delta connected. The slip ring three phase induction motor are started by inserting resistances so, the stator winding can be connected either in star or delta.

The winding wound on the stator of three phase induction motor is also called field winding and when this winding is excited by three phase ac supply it produces rotating magnetic field.

Types of Induction Motors Conclusion

After going through the above portion of types of induction motors we can now establish types of single phase induction motor and types of three phase induction motor. I hope you enjoy when reading this article, thank you.