MOTOR STARTER CIRCUIT INCLUDING SPARKLESS SWITCHES AND LOW-COST MOTOR PROTECTIONS FOR THREE PHASE INDUCTION MOTORS

摘要

PURPOSE: A three-phase motor starting circuit containing a switch without arcs and having a protection function is provided to prevent accumulated abrasion of a contact point by successively controlling each contact point. CONSTITUTION: A first relay (RLY1) connects or cuts off a first phase to or from the first winding of a three-phase motor. A second relay (RLY2) connects or cuts off a second phase to or from the second winding of the three-phase motor. A third relay (RLY3) connects or cuts off a third phase to or from the third winding of the three-phase motor. A third triac is connected to the third relay in parallel. A first comparator (104) detects the on/off of power.