Starting Methods of Single Phase Induction Motor？

Starting Methods of Single Phase Induction Motor？

Single-phase induction motor doesn’t have starting torque, so external circuitry is needed to provide this starting torque. The stator of these motors contains Auxiliary winding for this purpose. The Auxiliary winding is connected in parallel to a capacitor. When the capacitor is turned on, similar to the main winding, revolving two magnetic fields of the same magnitude but opposite direction are observed on Auxiliary winding.

From these two magnetic fields of Auxiliary winding, one cancels outs one of the magnetic fields of main winding whereas the other adds up with another magnetic field of main winding. Thus, resulting in a single revolving magnetic field with high magnitude. This produces force in one direction, hence rotating the rotor. Once the rotor starts rotating it rotates even if the capacitor is turned off.

There are different stating methods of single-phase induction motors. Usually, these motors are chosen based on their starting methods. These methods can be classified as

• Split-phase starting.

• Shaded-pole starting.

• Repulsion motor starting

• Reluctance starting.

In the split-phase starts, the stator has two types of windings – main winding and Auxiliary winding, connected in parallel. Motors with this type of starting methods are

• Resistor split-phase motors.

• Capacitor split -phase motors.

• Capacitors start and run motors.

• Capacitor-run motor.