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The motor is not self starting because the magnetic field acting on the rotor is just pulling and pushing, not rotating.

Amn interesting comparison is to get a piece of string about 1 foot long, with a weight tied on the end. Hold the other end of the string in your hand, and move your hand up and down. The weight will not rotate. However, if you stert it rotating, by using your other hand, the weight will now rotate, even if you only move your hand up and down.This works in both directions. If you want to be really clever, you can use 2 bits of string, and have them going in opposite directions at the same time.

To make the rotor rotate, a capacitor is used. This makes the current in that part of the circuit, lead the voltage by up to 90 degrees. This means you now have 2 fields, and since one is pulling and pushing just before the other, it makes the rotor rotate. Once the motor is running, a centrifugal switch opens to open-circuit the capacitor circuit.

It is also possible to do the same thing with an inductor. In this case, 1 of the windings is much more inductive than the other: more turns of thinner wire. The motor is now started in a similar, but opposite, manner to the capacitor, but will run in reverse.

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8y ago
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13y ago

Single phase induction motor can't produce continuously rotating magnetic field in the air gap, as either N or S pole would be present at a time. Single pole is not sufficient to drive the rotor from one end. So a capacitor is employed to split the phase, by which the stator becomes virtually 2 phase nd produces 2 poles at a time nd produces desired torque to run

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Q: Why single phase induction motor is not self starting?
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Self starting single phase induction motors are also called?

Split Phase Induction Motor.


How single-phase induction motor classified?

The single phase induction motors are made self starting by providing an additional flux by some additional means. Now depending upon these additional means the single phase induction motors are classified as: 1.Split phase induction motor. 2.Capacitor start inductor motor. 3.Capacitor start capacitor run induction motor. 4. Shaded pole induction motor.


How do you reverse single phase ac motor to generator?

how reversing an ac single phase induction motor to wark as induction generator


Will single-phase Induction motor run on one winding once it has been started?

A single-phase induction motor has a main winding and a starting winding. When the motor has run up to normal speed the starting winding can be switched out, but for small motors this is not usually worth the trouble.


Will a single-phase Induction motor run on one winding once it has been started?

A single-phase induction motor has a main winding and a starting winding. When the motor has run up to normal speed the starting winding can be switched out, but for small motors this is not usually worth the trouble.


What motor is used in a fan?

Single phase Induction motor


Is 3 phase induction motor is self starting?

Yes, that is one of the major advantages of a three-phase induction motor.


Revolving field theory of single phase induction motors?

revolving field theory of single phase induction motor


Do all single phase motors have a start and run winding?

No, commutator motors as used in vaccum cleaners for example do not use a starting winding. Single-phase induction motors need a starting winding without which they will start in either direction if given an initial twist.


Which motor is used in fans?

if you are asking about ordinary fans(used in home) . They consist single phase induction motor which require a capacitor for starting because single phase induction motar con not generate rotating tark to rotate the fan automatically


How do you start single phase induction motor?

capacitive start motors start by themselves however a normal single phase induction motor requires a starter motor to 'kick-start' the motor into action.


How is direction of rotation for single phase induction motor determined?

A single phase induction motor is not self starting; thus, it is necessary to provide a starting circuit and associated start windings to give the initial rotation in a single phase induction motor. The normal running windings within such a motor can cause the rotor to turn in either direction, so the starting circuit determines the operating direction.