What role does the centrifugal switch play in a capacitor-start motor?

The correct choice highlights the function of the centrifugal switch in a capacitor-start motor, which is to disconnect the starting winding once the motor achieves a predetermined speed. This mechanism is critical for the efficient operation of the motor.

In a capacitor-start motor, the starting winding is energized at startup to create an initial phase shift in the magnetic field, allowing the motor to start. As the motor accelerates and reaches approximately 70-80% of its full speed, the centrifugal switch activates. This switch is mechanically driven by the speed of the motor; when the specified speed is reached, the switch opens, disconnecting the starting winding from the circuit. This is essential because the starting winding is not designed to carry current during normal operation, and its continued engagement could lead to overheating.

Furthermore, disconnecting the starting winding at the right moment optimizes the performance of the motor and helps to prevent any potential damage associated with prolonged use of the starting circuit. Therefore, understanding the role of the centrifugal switch is vital for diagnosing issues related to starting and operational efficiency in capacitor-start motors.