At what speed does the centrifugal switch cut out the starter winding of a split-phase motor?

The centrifugal switch in a split-phase motor is designed to disconnect the starter winding when the motor reaches a certain speed, allowing the motor to run more efficiently on its main winding alone. This disconnection typically happens at approximately 75% of the motor's full speed.

At this speed, the motor has gained enough rotational momentum that the main winding can sustain operation without assistance from the starter winding. This is crucial because the starter winding is designed to help the motor start and achieve enough speed to switch over to the more efficient running phase. If the switch were to disengage at a lower speed, the motor might struggle to maintain operation, while disengaging at a higher speed could lead to unnecessary wear or overheating of components.

Therefore, recognizing that the centrifugal switch cuts out the starter winding at around 75% of full speed demonstrates an understanding of the operational principles of split-phase motors and their component interactions.