When a compressor is turned on, which motor winding is energized?

When a compressor is turned on, the start winding is energized first. This is crucial in providing the initial boost of torque necessary for the compressor to begin operation. The start winding is designed to create a phase shift in the electrical current, which enables the motor to generate sufficient torque to start up against the mechanical resistance of the compressor.

Once the compressor reaches a certain speed, a mechanism typically involving a relay will disconnect the start winding, allowing the motor to operate only on the run winding. This two-winding system helps improve the efficiency of the motor and ensures that it can start under load conditions without drawing excessive current.

In this system, the run winding can sustain the motor's operation, while the start winding is only utilized momentarily for that initial start-up phase. The other options, such as relay and capacitor, play supportive roles but are not directly energized at the start; the relay connects or disconnects the start winding, and capacitors may enhance performance but do not directly contribute to the initial energizing process.