The direction of rotation of a hysteresis motor is determined by
Right Answer is:
Position of shaded Pole with respect to the main pole
SOLUTION
The direction of rotation of a hysteresis motor is determined by the orientation of the main poles and the shaded poles.
Hysteresis motor
Single-phase cylindrical (non-salient-pole) synchronous-induction or shaded-pole motors are classed as hysteresis motors. Hysteresis motor is a single-phase synchronous motor without any projected poles and without DC excitation. Such motors start by virtue of the hysteresis losses induced in the hardened steel rotor by the rotating magnetic field produced by the stator winding and operate at synchronous speed due to the retentivity of the rotor core material.
Principle and Working
When a single-phase supply is given to the stator (split-phase type or shaded pole type), a revolving magnetic field is set up by it. Eddy currents are induced in the rotor. These eddy currents set up the rotor magnetic field which causes the rotor to rotate. A high starting torque is produced as a result of the high rotor resistance (proportional to the hysteresis loss). As the motor approaches synchronous speed, the frequency of current reversal in the crossbars decreases, and the rotor becomes permanently magnetized in one direction.
The direction of rotation of a hysteresis motor is determined by the orientation of the main poles and the shaded poles.
