Understanding Split-Phase Induction Motor Stator Windings

A split-phase induction motor is a type of single-phase AC motor commonly used in various applications. Its distinctive feature is the method used to initiate rotation, which requires creating a rotating magnetic field within the stator.

To achieve this, the stator of a split-phase induction motor is equipped with 2 windings:

• Main Winding (or Running Winding): This winding is constructed with relatively few turns of thicker copper wire. It possesses high inductance and low resistance. Its primary role is to sustain the motor's operation once it has reached its running speed.
• Auxiliary Winding (or Starting Winding): This winding consists of more turns of thinner wire compared to the main winding. It has lower inductance and higher resistance. This design helps create a phase difference between the currents flowing through the main and auxiliary windings, which generates the necessary starting torque. The auxiliary winding is typically connected in series with a centrifugal switch or a capacitor, which automatically disconnects it from the circuit once the motor attains about 75% to 80% of its rated speed.

The spatial arrangement and electrical characteristics of these two windings allow the motor to produce a starting torque, enabling it to begin rotating. Once running, the main winding primarily handles the motor's operation. Thus, the fundamental configuration includes these two essential stator windings.