Vacuum motor control including float switch and in-rush current restraint

摘要

A soft start power control device for a liquid vacuum motor includes a detection component for shutting off the vacuum motor when the vacuum's recovery tank reach full capacity, and in-rush current limiting component for restraining the in-rush current to the motor when the power is switched on, whereby the motor slowly ramps up to its operating speed. The motor is switch by a triac. The device includes a component for preventing the triac from inadvertently triggering at commutation frequency. A snubber circuit is also connected in parallel with the triac to limit the dv/dt characteristic. The detection component includes a float switch to monitor the level of liquid in the recovery tank. The detection component disables the motor once the water reaches a predetermined high level, which then requires the operator to empty the recovery tank before restarting the motor.