Induction Motor diagram and Application
1. Split phase induction motor
2. Capacitor start induction motor
3. Capacitor start capacitor run induction motor
4. Shaded pole induction motor
1. Split phase induction motor
Stator of single phase induction motor is divided into two winding Main winding and Auxiliary winding or Starting winding . A centrifugal switch is connected in series with Starting winding. The purpose of this switch is to disconnect the starting winding from main winding from the main circuit when the motor attains a speed up to 75 to 80 % of the synchronous speed. We know that the running winding is inductive in nature. Our aim is to create the phase difference between the two winding and this is possible if the starting winding carries high resistance.
Application
Split phase motors used ind small grinders, small fan, and blowers, and other low starting torque application with power needs from 1/20 to 1/3 hp .
2. Capacitor start induction motor
If a capacitor is connected in series with the starting winding, the phase angle between the two winding currents will become more than 30 degree (about 80 degree) that is obtained in the split phase motors. This increases in phase angle will increases the starting torque. Fig shows the capacitor start motor.
Application
Because of their higher starting torques, capacitor start motors are used in applications where not only higher starting torques are required ,but also where reversible motors are needed . Typical applications are washing machine, belted fans and blowers, dryers,pumps and compressors.
3. Capacitor start capacitor run induction motor
The working principal and construction of capacitor start induction motor and capacitor start capacitor run induction motor is almost same.
We already know that single phase induction motor is not self starting because the magnetic field produced is not rotating type. In order to produce rotating magnetic field there must be some phase difference. In case of split phase induction motor we use resistance for creating phase difference but here we use capacitor for this purpose. We are familiar with this fact that the current flowing through the capacitor leads the voltage. So, in capacitor start inductor motor and capacitor start capacitor run induction motor we are using two winding, the main winding and the starting winding
4. Shaded pole induction motor
The stator of the shaded pole single phase induction motor has salient or projected poles. These poles are shaded by copper band or ring which is inductive in nature. The poles are divided into two unequal halves. The smaller portion carries the copper band and is called as shaded portion of the pole.
When a single phase supply is given to the stator of shaded pole induction motor an alternating flux is produced . This change of flux induces emf in the shaded coil. Since this shaded portion is short circuited, the current is produced in it in such a direction to oppose the main flux. The flux in shaded pole lags behind the flux in the unshaded pole. The phase difference between these two fluxes produces resultant rotating flux.
Application
Due to their low starting torques and reasonable cost these motors are mostly employed in small instruments, hair dryers, toys, record players, small fans, electric clocks etc. These motors are usually available in a range of 1/300 to 1/20 KW.