Repulsion induction motor
This type of motor is a combination of repulsion motoron motor and induction motor. It is also referred as squirrel cage repulsion motor.
This motor possesses the characteristic of both induction motor and repulsion motorulsion motor . It combines the desirable starting characteristics of repulsion motor and constant speed characteristics of an induction motor.
Here the stator winding is same as every other repulsion motor but there are two separate rotor windings
· A squirrel cage winding
· A Commutator winding
The commutator winding lies on the outer slots while the squirrel cage winding is located in the inner slots. Both the windings operate during the entire period of operation of motors. The brushes are in contact with the commutator all the time.
The biggest advantage in such type of motors is that they don’t need a separate centrifugal short-circuit system as in Repulsion-start Induction-run motors.
As soon as the motor is started, the squirrel cage winding is practically inactive for a small period of time due to high reluctance. Only the commutator winding supplies most of the torque. But during normal running condition, the squirrel cage winding supplies most of the torque and commutator winding supplies relatively lower torque when compared to Squirrel cage winding. So the squirrel cage winding takes up most of the load as the rotor accelerates.
The starting torque is very high with better speed regulation.
· Petrol pumps
· Mixing machines
· Lifts and Hoists
But now a days brushless repulsion motors are preferred to reduce the amount of wear and tear and frictional losses that occur at the brush terminals.