How does a split-phase motor start?

A split-phase motor starts by utilizing a secondary winding to create a phase difference. This motor configuration includes two windings: the main winding and a start (or auxiliary) winding. When the motor is powered, the current in these two windings creates a magnetic field that is out of phase. This phase difference is crucial because it generates a rotating magnetic field, which is essential for initiating the motor's rotation.

The main winding provides the necessary torque to keep the motor running once it has started. However, the auxiliary winding is only activated during startup and is typically deactivated (disconnected) by a centrifugal switch or a relay once the motor reaches a specific speed. This action prevents overheating and inefficiencies that could occur if both windings were used continuously.

The other options do not accurately describe the starting mechanism of a split-phase motor. Utilizing a single winding for initiation would not create the necessary phase shift for starting. An external starter mechanism is not typically used for split-phase motors; they are designed to start internally. Gradually increasing the voltage is also not a method used by split-phase motors to start; rather, they require a defined phase difference established by the two separate windings to begin rotation effectively.