The centrifugal switches are mainly applied for switching off the auxiliary phase. The function is to switch off the auxiliary phase of single-phase motors, before reaching the normal running speed. For safety reasons the switch-off is proceeded at 80% of the synchronous motor speed.
How does it work?
When the motor is in standstill position, the contacts of the switch are closed. At this time, the auxiliary phase is hooked up and the motor is ready to start. When switching on the motor, the run-up is done with the main phase and the auxiliary phase simultanously. When it reaches the breaking speed the auxiliary phase will cut off. The motor finally reaches its normal running speed without the auxiliary phase. During run-up the motor needs high currents. Therefore the auxiliary phase is broken with relative high currents as well. If capacitors are used for the auxiliary phase there will be additional high voltages. This causes very high requirements for the switching ability of the centrifugal switch. The switches manifactured by Vosseler meet these requirements execellently.