Why Capacitor is used in Single phase Induction Motor?Full Explanation.

Why Capacitor is used in Single phase Induction Motor?

Nowadays single-phase motors are widely used in our houses, office, and other areas. The single-phase motor becomes very popular as it is low-cost. 

There are three types of Single Phase Motor

1. Induction motors
2. Commutator motors
3. Synchronous motors

You may notice that every single-phase induction motor (except the Shaded pole Induction Motor) need one or more capacitor. So today we are going to know Why Capacitor is used in Single-phase Induction Motor? or Why Capacitor is used in Fan?

Why Capacitor is Used in Single-phase Induction Motor: The answer is that as the single-phase induction motor is not self-starting so the capacitor is used to make the single-phase induction motor self-starting.

Why Single Phase Induction Motor is not self-starting?

The Single Phase Induction Motor is not self-starting because if we give a single-phase AC supply to the stator winding of the single-phase induction motor the stator winding produces alternating flux and for the transformer action, an alternating emf is produced on the rotor winding which causes to flow alternating current in the rotor winding. 

So an alternating flux was also produced in the rotor winding which tried to oppose the stator emf. Therefore no torque will develop in the rotor. So when we give a single-phase AC supply the motor does not start rotating it will vibrate. So for this reason capacitor is used in Ceiling Fan as well as any single-phase induction motor.

How to start a single-phase induction motor?

After giving the single-phase AC supply if we push the rotor by hand or by another means in either direction, it will pick up the speed and continue to rotate in the same direction developing operating torque.

How does the Capacitor make the single-phase induction motor self-starting?

To make the single-phase induction motor self-starting we need to add an extra winding which is called starting winding. And the winding will be connected in series with a capacitor. By using a capacitor of proper value, the starting winding current can be made to lead the main winding current by 90^o. That means the capacitor creates a phase difference between the two windings and the starting winding pushes the rotor to start rotating.

Single Phase motor connection with Capacitor Diagram:

The below circuit diagram is of the Permanent Capacitor single phase Induction motor. This is also the circuit diagram of a ceiling fan.

What type of motor is used in Ceiling Fans?

Single phase squirrel cage capacitor starts capacitor run induction motor used in Ceiling Fan.

How to connect the capacitor to the ceiling fan?

At first measure the resistance of each winding. The starting winding has less resistance than the running winding. Then connect the capacitor according to the above circuit diagram. You can see the capacitor is connected in series with starting winding.

Which type of Capacitor is used in Ceiling Fans?

Mainly Oil filled capacitor used in ceiling Fan. Nowadays, the dry capacitor with high insulation is used in the ceiling fan. 

How to change the direction of rotation of single-phase induction motor?

To change the direction of rotation of the single-phase induction motor reverse the connection of any one winding either starting winding or running winding.

Which type of single-phase induction motor can run without a capacitor?

The shaded pole induction motor can run without the capacitor.

Read Also:

• Can DC Motor run on AC supply and Vice-Versa? Full Explanation.
• Shaded Pole Induction Motor Working and Application Explained
• Difference between Generator and Alternator Full explanation.
• AC Motor VS DC Motor | Difference with Advantage and Disadvantage
• Why Alternator Armature Winding always connected in STAR?
• Actual Difference between Servo Motor and Stepper Motor

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