Why induction motor is self starting

The reason behind this is very interesting. Phase induction motor is self starting. Because if they are not, they are not usually considered ot be machines, but rather, candidates for the title boat anchor.

The working principle of an ac machine is primarily one field following another field. Thus we see that Induction Motor is self-starting.

It does not require nay external mean to rotate.

However, in this case, the rotor has its own field produced by .

Let see what are the Most important points that one should know about induction motor. This video deals with Concepts of Rotor mmf,air gap flux ,stator and r. There are basically two types of induction motor that depend upon the input supply - single phase induction motor and three phase induction motor. Now at starting, both the forward and backward components of flux are exactly opposite to each other.

Also both of these components of flux are equal in magnitude. So, they cancel each other and hence the net torque experienced by the rotor at starting is zero. So, the single phase induction motors are not self starting . During the positive half cycle the rotor will rotate in one direction and in negative half cycle it rotates opposite to that. So the net torque developed is zero and hence single phase induction motor is not self starting.

DC motors are self starting because the angle between the magnetic field of the rotor and the stator is fixed by the design of the motor. Why single phase induction motor is not self starting ? This in the flow of current . Although polyphase motors are inherently self - starting , their starting and pull-up torque design limits must be high enough to overcome actual load conditions. To overcome this drawback and make the motor self starting , it is. Figure below) however, it will not self start.

Single-phase induction motors are not self - starting without an auxiliary stator winding driven by an out of phase current of near 90o. Once started the auxiliary winding is optional. In case of three phase AC operation, most widely used motor is Three phase induction motor as this type of motor does not require any starting device or we can say they are self starting induction motor. Why are induction machines self starting?

As we know about synchronous motor, it runs with the speed of supply frequency or with speed of rotating magnetic field. But If it make self starting then then it function become similar as induction motor and the purpose of synchronous ( leading power factor) defeated. A three phase induction motor is inherently self starting , while single phase induction motor can be made to be self starting by using capacitors and auxiliary windings. In thats point of view,you can call it synchronous motor. Now,as synchronous motor,reluctance motor also is not self starting.

So,we provide shorted copper bar in rotor (as like as induction motor ). Hence ,it is self started like induction motor. Hence, this motor is called sometimes by “synchronous induction motor ”. Various starting methods used in the single-phase induction motors , with the intro - duction of additional features, like the.