Select the INCORRECT option with respect to repulsion type motor.

Repulsion Type Motor:

• The stator of the repulsion type motor is the same as the split-phase induction motor.
• The armature of the rotor is similar to the DC motor armature with drum-type winding connected to the commutator.
• Pair of brushes are used and it short-circuited to make a rotor squirrel cage.
• By changing the position of brushes starting torque can be varied.
   

Operating Principle of Repulsion Motor:

• When supply is given to the stator winding then the alternating field produced in the air gap.
• By means of transformer action, EMF induced in the armature conductor.
• However, the direction of the induced current in the armature conductor will depend on the position of the short-circuited brushes pair.
• When the brush axis is parallel or perpendicular to the magnetic axis then no torque will be developed because the net voltage developed in the armature conductor is zero.
• For the production of torque in the rotor, we have to place the short-circuited brushes between 0° to 90° say α with respect to the magnetic axis.

Armatur torque(T_a) = k sin (2α)

When α is 45° than maximum torque will be produced.

• It has high starting torque, low starting current, and better power factor than a single-phase induction motor.
• But it has the disadvantage that it operated at a low power factor when the speed is less.