What happens to the starting winding in a motor when the centrifugal switch engages?

When the centrifugal switch engages in a motor, it disconnects the starting winding from the circuit. The purpose of the starting winding is to help the motor start. Once the motor reaches a certain speed—typically around 70-80% of its rated speed—the centrifugal switch activates due to the centrifugal force generated by the rotating motor shaft. This action ensures that the starting winding is removed from the electrical circuit, allowing the motor to run efficiently and preventing overheating or potential damage due to the starting winding remaining engaged during normal operation.

The disconnecting of the starting winding is crucial because it allows the motor to run on just the main winding, which is designed for continual operation. Maintaining the starting winding connected could lead to excessive current draw and overheating, ultimately leading to failure. Understanding this mechanism is important for anyone working with electric motors, particularly in lineman apprenticeships, as it is fundamental to motor operation and safety.