single phase induction motor
There are probably more single-phase ac induction motors in use today than the total of all the other types put together.
But what's single phase induction motor?
In a single phase induction motor, it is necessary to provide a starting circuit to start rotation of the rotor. If this is not done, rotation may be commenced by manually giving a slight turna high value, reducing the current through the second winding to an insignificant level. Other designs keep the second winding continuously energised during running, which improves torque.
The single-phase ac induction motor is the least expensive, lowest maintenance type of ac motor.
Unlike the polyphase induction motors, the stator field in the single-phase motor does not rotate. Instead it simply alternates polarity between poles as the ac voltage changes polarity.
Voltage is induced in the rotor as a result of magnetic induction, and a magnetic field is produced around the rotor. This field will always be in opposition to the stator field (Lenz's law applies). The interaction between the rotor and stator fields will not produce rotation.
