Single-phase motors

Abstract

Many small a.c. motors will be designed to operate from a single-phase supply and will take the form of single-phase induction motors or a.c. commutator motors. The single-phase squirrel-cage induction motor is the most widely used form of machine but suffers from the disadvantage, noted in chapter 1, that it produces no starting torque. In order to produce starting torque, a second stator winding will normally be introduced so that, during the starting period, the machine operates as an asymmetrical 2-phase motor connected to a single-phase supply. In these circumstances, the operation of the symmetrical polyphase machine on a single-phase system can be used to illustrate the principles underlying the performance of single-phase induction motors.