Electrical Engineering ⇒ Topic : Repulsion-induction motor

REPULSION-INDUCTION MOTOR

A single-phase repulsion-induction motor combines the constant-speed characteristics of the single-phase induction motor with the good starting characteristics of the repulsion motor.

The stator of this machine has a simple single-phase winding like that of single-phase induction motor. The rotor, however, is built up of laminations, each of which has two concentric sets of slots. These slots contain two distinct windings ; in-the outer slots is wound a commutator winding similar to that of a D.C. armature, while in the inner slots is a cast aluminium squirrel-cage winding which clamps the laminations

Fig (a) illustrates an armature for a repulsion induction motor complete with a squirrel-cage winding.

                                                      Fig.(a) Repulsion induction motor.

At starting and during the acceleration period, the magnetic flux produced by the stator embraces only the commutator winding in the outer slots owing to the high reactance of the squirrel cage.The motor starts up virtually as a repulsion motor and develops a high starting torque. As the motor speeds up the reactance of the squirrel-cage decreased, so that this winding assists the commutator winding to supply the running torque.