- A single phase supply cannot produce rotating magnetic field rather it produces a pulsating magnetic field which does not rotate.
- Hence because of the pulsating magnetic field, the net torque on rotor is zero.
- To make it self-starting, we should somehow produce a revolving stator magnetic field. This may be achieved by converting a single-phase supply into two- phase supply through the use of an additional winding. When the motor attains sufficient speed, the starting means (i.e., additional winding) may be removed depending upon the type of the motor.
- The single phase induction motors are classified based on the method used for self starting-
(i) Split-phase motors-started by two phase motor action through the use of an auxiliary or starting winding.
(ii) Capacitor start motors-started by two-phase motor action through the use of an auxiliary winding and a capacitor.
(iii) Capacitor start Capacitor run motors-started by two-phase motor action through the use of an auxiliary winding and two capacitors.
(iv) Shaded-pole motors-started by the motion of the magnetic field produced by means of a shading coil around a portion of the pole structure.
Electrify Students 