Introduction:
The centrifugal switch is an important component in a motor's starting mechanism. It is designed to disconnect the starting winding from the power supply once the motor reaches a certain speed, typically around 70 to 80 percent of its synchronous speed. This disconnection is necessary to prevent damage to the starting winding and ensure the motor operates efficiently.

Explanation:
When a motor starts, it initially requires a higher starting torque to overcome the inertia and bring the rotor up to speed. This higher torque is provided by the starting winding, which is typically connected in series with a capacitor. The starting winding is designed to have a higher resistance and lower reactance compared to the running winding.

Role of the centrifugal switch:
The centrifugal switch is a mechanical device connected to the motor shaft. It consists of two contacts that are normally closed when the motor is at rest or rotating at a low speed. As the motor accelerates, the centrifugal force generated by the rotating shaft causes the switch to open, disconnecting the starting winding from the power supply.

Importance of opening at the right speed:
If the centrifugal switch fails to open at the specified speed (70 to 80 percent of synchronous speed), it can have several negative consequences:

1. Damage to the starting winding: The starting winding is not designed to operate continuously at full voltage. If it remains connected to the power supply beyond the recommended speed, excessive current will flow through the winding, leading to overheating and potentially damaging the winding insulation. This can result in short circuits, open circuits, or even complete failure of the starting winding.

2. Overloading of the running winding: The running winding, which is responsible for the motor's normal operation, may also experience excessive current if the starting winding remains connected for too long. This can lead to overheating and increased power consumption, potentially causing damage to the winding and reducing the motor's efficiency.

3. Damage to the centrifugal switch: If the centrifugal switch fails to open at the specified speed, it may be subjected to excessive mechanical stress due to the high centrifugal forces acting on it. This can lead to premature wear and failure of the switch, requiring replacement or repair.

Conclusion:
In summary, if the centrifugal switch fails to open at 70 to 80 percent of the synchronous speed of the motor, it can result in damage to the starting winding, overloading of the running winding, and potential damage to the centrifugal switch itself. Therefore, it is crucial to ensure that the centrifugal switch is functioning properly and disconnects the starting winding at the appropriate speed to prevent these issues and ensure the motor operates efficiently.