Correct Answer - Option 4 : Opaque pole type
Single-phase induction motor:
- The Single-phase induction motor is not self-starting. Hence it requires starting circuit
- It will rotate in the direction of the magnetic rotation provided by starting or auxiliary winding and capacitor.
- When AC is supplied to the stator of a single-phase induction motor, it produces flux of magnitude ϕm.
- According to the double field theory, this alternating flux ϕm is divided into two components of magnitude ϕm / 2 each and rotate in the opposite direction, with the synchronous speed NS.
- The resultant of these two components of flux at any instant of time gives the value of instantaneous stator flux at that particular instant.
- At starting both the flux components are exactly opposite to each other and are equal in magnitude. So, they cancel each other and hence net torque produces by the rotor at the starting condition is zero and single-phase induction motor is not self-starting.
- Hence, to start the motor starting windings are used.
Depending upon starting methods used in single-phase induction motor, types of motor is-
i. Split phase induction motor
ii. Capacitor start (electrolyte capacitor used)
iii. Capacitor start-capacitor run motor
iv. Shaded pole induction motor
v. Permanent split capacitor motor