Circuit interrupting means for a high voltage direct-current circuit with means for reducing the severity of the recovery voltage

Claim 1

MEANS FOR INTERRUPTING A HIGH VOLTAGE D.-C. CIRCUIT THAT COMPRISES A SMOOTHING REACTOR CONNECTED IN SERIES WITH A LOAD ACROSS A SOURCE OF DIRECT CURRENT, COMPRISING: (A) A CIRCUIT INTERRUPTER ADAPTED TO BE ELECTRICALLY LOCATED BETWEEN SAID REACTOR AND SAID LOAD AND COMPRISING RELATIVELY MOVABLE CONTACTS FOR CONNECTION IN SERIES WITH SAID REACTOR AND SAID LOAD, (B) MEANS FOR NORMALLY MAINTAINING SAID CONTACTS IN ENGAGEMENT TO ENABLE LOAD CURRENT TO FLOW THERETHROUGH, (C) ARC-INITIATING MEANS FOR SEPARATING SAID CONTACTS TO DRAW AN ARC THEREBETWEEN, (D) A NORMALLY-OPEN ARC-QUENCHING CIRCUIT CONNECTED ACROSS SAID CONTACTS AND COMPRISING NORMALLY-OPEN CIRCUIT-MAKING MEANS AND A COMMUTATING CAPACITOR CONNECTED IN SERIES CIRCUIT RELATIONSHIP WITH EACH OTHER, (E) MEANS FOR PRECHARGING SAID COMMUTATING CAPACITOR, (F) MEANS FOR FORCING THE CURRENT THROUGH SAID ARC TO ZERO COMPRISING MEANS RESPONSIVE TO OPERATION OF SAID ARC-INITIATING FOR CLOSING SAID CIRCUIT-MAKING MEANS UPON INITIATING OF SAID ARC TO DISCHARGE SAID COMMUTATING CAPACITOR THROUGH SAID SEQUENCHING CIRCIUT AND THROUGH SAID ARC IN A DIRECTION OPPOSITE TO THE DIRECTION OF LOAD CURRENT THERETHROUGH, (G) AND MEANS FOR LIMITING THE MAGNITUDE AND FREQUENCY OF THE RECOVERY VOLTAGE APPEARING ACROSS SAID CIRCUIT INTERRUPTER WHEN THE CURRENT THERETHROUGH IS FORCED TO ZERO COMPRISING THE SERIES COMBINATION OF A NORMALLY-OPEN GAP DEVICE AND A RESISTOR CONNECTED ACROSS SAID SMOOTHING REACTOR, AND MEANS FOR CAUSING SAID GAP DEVICE TO BREAK DOWN AND EFFECTIVELY CONNECT SAID RESISTOR ACROSS SAID REACTOR IMMEDIATELY AFTER THE CURRENT THROUGH SAID INTERRUPTER REACHES ZERO.