During the operation of a capacitor-start motor, what happens when the start switch opens?

When the start switch opens in a capacitor-start motor, the primary action is the removal of the start capacitor from the circuit. This is crucial because the start capacitor is designed to provide the necessary boost of energy for the motor to start up efficiently. Once the motor reaches a certain speed, typically around 70-80% of its rated speed, the start switch opens, cutting off the power to the start capacitor.

Removing the start capacitor is important because it is not intended to be used during the normal running of the motor; its role is purely for initial startup. If the start capacitor were to remain in the circuit, it could lead to overheating or inefficiencies, ultimately risking damage to the motor. Hence, the action of opening the start switch ensures that the start capacitor is disconnected, allowing the motor to run smoothly with just the run winding for normal operation.