Final answer:
The centrifugal switch removes the start capacitor from the circuit when the compressor approaches 75% of its synchronous speed.
Step-by-step explanation:
In an electrical circuit, the start capacitor is used to provide an initial boost of power to start the compressor. However, once the compressor approaches 75% of its synchronous speed, a device called a centrifugal switch is activated and it removes the start capacitor from the circuit.
The centrifugal switch is typically a mechanical switch that is connected to the compressor. It is designed to detect the rotational speed of the compressor. Once the compressor reaches 75% of its synchronous speed, the centrifugal force causes the switch to open and disconnect the start capacitor from the circuit.
This mechanism is important because the start capacitor is only needed during the initial startup phase to overcome the high starting torque required by the compressor motor. Once the compressor reaches a certain speed, the start capacitor becomes unnecessary and could cause damage if left in the circuit for too long.