What happens to the stator winding of a single-phase motor when voltage is applied?

When voltage is applied to the stator winding of a single-phase motor, it remains stationary. This occurs because single-phase motors rely on the interaction between the stator magnetic field and the rotor to initiate motion. In a single-phase system, the alternating current creates a magnetic field that oscillates, but it does not create a rotating magnetic field like in three-phase motors.

Due to this lack of a rotating magnetic field, the stator alone cannot generate the necessary torque to turn the rotor when the voltage is first applied. The rotor will start turning only when additional mechanisms, such as a starting capacitor or auxiliary winding, are employed to create a temporary phase shift in the current, allowing the motor to start rotating.

The other options suggest different behaviors that do not accurately describe the functioning of a single-phase motor’s stator when voltage is applied. For instance, it doesn’t rotate because it lacks a rotating magnetic field, nor does it increase resistance significantly or short circuit under normal operation conditions. Understanding this principle is essential in HVACR applications for effectively diagnosing and working with single-phase motors.