Construction and Working Principle of Single Phase Induction Motor

CONSTRUCTION AND WORKING PRINCIPLE OF SINGLE PHASE INDUCTION MOTOR

The single phase motors are simple in construction and small in size. These motors have power rating in fractional horse power range. They are used in fans, washing machines, hand tools like drivers, record player, refrigerators, juice makes etc. The main disadvantages are lack of starting torque, reduced power factor, low efficiency.

Construction

Single phase induction motor consists of two parts. One is stationary part which is called as stator and the other is rotating part which is called as rotor. The air gap between stator and rotor is uniform. There is no external connection between stator and rotor.

A single phase winding would not produce a rotating magnetic field and starting torque. It is necessary to split the stator winding into two parts. Such that it will be displaced in space on the stator to make the motor self starting.

Working Principle

When single phase supply is given to the stator winding, an alternating field is produced. This alternating field will induce an emf in the rotor conductors by the principle of mutual induction so the rotor has a closed circuit, current flowing through the rotor conductors.