Controlled rectifier d. c. switching circuit

Claim 1

A SWITCHING CIRCUIT INCLUDING IN COMBINATION A PAIR OF CONTROLLED RECTIFIERS EACH HAVING CONTROL GATE ELEMENTS, A FIRST OF SAID CONTROLLED RECTIFIERS BEING ADAPTED TO BE CONNECTED IN SERIES CIRCUIT RELATIONSHIP WITH A LOAD DEVICE ACROSS A SOURCE OF ELECTRIC ENERGY, A QUENCHING CIRCUIT INCLUDING A QUENCHING CAPACITOR CONNECTED IN SERIES CIRCUIT RELATIONSHIP WITH SAID REMAINING CONTROLLED RECTIFIER AND ADAPTED TO DIVERT LOAD CURRENT FROM SAID FIRST CONTROLLED RECTIFIER, A CHARGING DEVICE CONNECTED IN CIRCUIT RELATIONSHIP WITH SAID QUENCHING CAPACITOR FOR PRECHARGING SAID QUENCHING CAPACITOR WITH A POTENTIAL HAVING A POLARITY SUCH THAT ITS NEGATIVELY CHARGED PLATE IS CONNECTED TO THE POSITIVE ELECTRODE OF SAID FIRST MENTIONED CONTROLLED RECTIFIER, AN ON TRIGGERING CIRCUIT COUPLED TO THE GATE ELEMENT OF THE FIRST CONTROLLED RECTIFIER FOR SWITCHING THE CIRCUIT TO ITS ON CONDITION, AN OFF TRIGGERING CIRCUIT COUPLED TO THE GATE ELEMENT OF THE REMAINING CONTROLLED RECTIFIER FOR TURNING ON SAID REMAINING CONTROLLED RECTIFIER AND THEREBY SWITCH THE CIRCUIT TO ITS OFF CONDITION AND AN OVERLOAD SENSING DEVICE CONECTED IN SERIES CIRCUIT RELATIONSHIP WITH THE LOAD DEVICE FOR SENSING AN OVERLOAD CONDITION INSTANTANEOUSLY, SAID OVERLOAD SENSING DEVICE BEING ELECTRICALLY COUPLED TO THE CONTROL GATE ELEMENT OF SAID REMAINING CONTROLLED RECTIFIER FOR TURNING OFF THE CIRCUIT INSTANTANEOUSLY IN RESPONSE TO AN OVERLOAD CONDITION.