Control system for power units such as electric motors and the like

Claim 1

IN A CONTROL SYSTEM FOR CONTROLLING ENERGIZATION OF A MOTOR OR THE LIKE FROM A MULTI-PHASE POWER SOURCE COMPRISING IN COMBINATION A MAIN SWITCH FOR COUPLING THE SOURCE TO THE MOTOR, SIGNAL PRODUCING MEANS FOR SENSING CURRENT FLOW IN EACH PHASE TO THE MOTOR AND A CIRCUIT RESPONSIVE TO SIGNALS FROM SAID SENSING MEANS FOR CONTROLLING OPERATION OF SAID MAIN SWITCH, SAID CIRCUIT MEANS INCLUDING ELECTROMECHANICAL MEANS AND A FIRST SWITCH FOR SELECTIVELY COUPLING SAID MEANS INTO SAID CONTROL CIRCUIT, SAID ELECTROMECHANICAL MEANS RESPONSIVE TO ENERGIZATION TO EFFECT OPERATION OF SAID SWITCH MEANS TO CONNECT SAID SOURCE TO SAID MOTOR, RESPECTIVE SECOND AND THIRD SWITCH MEANS RESPONSIVE TO RESPECTIVE PREDETERMINED HIGH AND LOW ENERGY LEVEL SIGNALS FROM SAID SENSING MEANS AND COUPLED TO SAID ELECTROMECHANICAL MEANS TO DEENERGIZE THE LATTER UPON SENSING OF SUCH RESPECTIVE HIGH AND LOW ENERGY SIGNALS, AND A PAIR OF TIME DELAY BY-PASS SWITCHES, ONE FOR EACH OF SAID RESEPCTIVE HIGH AND LOW SET-POINT SWITCHING MEANS, FOR INITIALLY DISABLING THE LATTER AND OPERATIVE AFTER RESPECTIVE PREDETERMINED TIME DELAYS TO MAKE SAID ENERGY LEVEL RESPONSIVE SWITCHES EFFECTIVE, SAID HIGH SET-POINT BY-PASS DELAY TIME PERIOD BEING SHORTER THAN SAID LOW SET-POINT BY-PASS DELAY TIME PERIOD SO AS TO PERMIT ENERGY FLOW TO SAID MOTOR TO RISE ABOVE SAID LOW SET-POINT AT STARTING WHILE ASSURING THAT AN INITIAL EXCESS OF ENERGY FLOW EFFECTS DEENERGIZATION OF SAID MOTOR.