What is the main purpose of a starting or auxiliary winding in motor operation?

The main purpose of a starting or auxiliary winding in motor operation is to enable starting torque. In many types of single-phase induction motors, a starting winding is used to create a phase shift in the current, which is essential for generating a rotating magnetic field. This rotating field is necessary to produce the initial torque that gets the motor up and running.

When the motor starts, the auxiliary winding is energized, and it creates a second magnetic field that is out of phase with the main winding. This interaction is what allows the motor to begin turning. Once the motor reaches a certain speed, typically a designated operating speed, a switch or relay disconnects the auxiliary winding, allowing the motor to run efficiently with just the main winding.

The other options may describe benefits that could arise from having auxiliary windings in some indirect way, but they do not capture the primary role. Enhancing efficiency can occur when the motor is running but is not the main purpose of the starting winding. Similarly, reducing wear on the main winding and improving speed regulation are not direct functions of the auxiliary winding during the starting phase. The focus of the auxiliary winding's design is specifically on providing the necessary torque to start the motor effectively.