Why the Rotor of Induction Motor is Skewed? Need of Skewing

The Rotor of Induction Motor is skewed to prevent the Cogging Phenomenon. This is the main reason. For the skewing of the rotor of the induction motor, there are also some additional advantages. In this article, we will discuss what is skewing, how skewing of the rotor prevents the Cogging and the additional advantages of skewing. So let's discuss it in detail.

What is Skewing of Rotor?

In the induction motor rotor, the slots for the placement of conductors are not made exactly in parallel with the rotor shaft. A slight angle is maintained that means the rotor slots are made in some angle with the rotor shaft. This is called Skewing of the rotor or Skewed Rotor.

What is Skewing of rotor in Induction Motor, Skewed Rotor

In the above figure, you can see there are two types of the rotor are shown, the left side rotor is the unskewed rotor that means the slots are made exactly in parallel with the rotor shaft. The right side rotor is the skewed rotor. Here you can see the slots are made maintaining a slight angle. So the right side skewed rotor is used in Induction motor.

What is Cogging?

The main reason for using a skewed rotor is to prevent the Cogging. So let's discuss what is Cogging in Induction Motor. In simple words, Cogging is the phenomenon of the magnetic locking between Stator and Rotor of Induction Motor. This magnetic locking occurs when the number of stator slots is equal to the number of rotor slots.

How Skewing of Rotor Eliminate the Cogging?

When the rotor is skewed or the slots are made in some angle, the magnetic locking between stator and rotor is eliminated. As the slots are made in some angle, that means the aluminum bars (Which used as conductors) also placed in some angle. So when the magnetic flux is produced by the stator winding, the rotor bars cut the flux uniformly. The next bar starts cutting the magnetic flux before finishing the cutting of flux by the previous bar. So this continuous flux cutting creates a continuous torque on the rotor and eliminates the chance of magnetic locking.

Advantages of Skewing of Rotor in Induction Motor

1.The first and main advantage is the elimination of Cogging or magnetic locking.

2.As the skewing of the rotor is to reduce the magnetic locking, so the magnetic hum (vibration and sound) is also reduced.

3.It causes the production of uniform flux in the rotor, for this reason, the induction motor runs uniformly.

4.It increases the effective coupling between Rotor and Stator fluxes.

5.It also helps to reduce the Crawling in Induction Motor.

6.As the conductors are placed in some angle, the length of the conductor's increases, therefore the effective rotor resistance increases which help to create more torque on the rotor.

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Why the Rotor of Induction Motor is Skewed? Need of Skewing Why the Rotor of Induction Motor is Skewed? Need of Skewing Reviewed by Author on June 20, 2019 Rating: 5
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