Compressed gas actuated circuit breaker having a dwell phase in the opening stroke of the movable contact

Claim 1

IN A COMPRESSED GAS ACTUATED CIRCUIT BREAKER HAVING A CLOSED GAS CIRCUIT, THE COMBINATION COMPRISING MEANS PROVIDING A HIGH PRESSURE CHAMBER FILLED WITH AN ARC EXTINGUISHING GASEOUS MEDIUM SUCH AS SF6, MEANS PROVIDIN A LOW PRESSURE CHAMBER SEPARATED FROM SAID HIGH PRESSURE CHAMBER BY A SUPPORT INSULATOR, A STATIONARY CONTACT MEMBER IN THE FORM OF A NOZZLE MOUNTED BY SAID SUPPORT INSULATOR AND THROUGH WHICH THE COMPRESSED GAS CAN FLOW IN PASSING FROM SAID HIGH PRESSURE CHAMBER TO SAID LOW PRESSURE CHAMBER FOR COLLECTION IN THE LATTER, A MAIN DRIVE CYLINDER MOUNTED IN SAID HIGH PRESSURE CHAMBER, THE WALL OF SAID CYLINDER BEING PROVIDED WITH AN APERTURE PLACING THE INTERIOR AND EXTERIOR OF SAID CYLINDER IN COMMUNICATION WITH EACH OTHER, A COMPRESSED GAS ACTUATED HOLLOW DRIVE PISTON MOUNTED FOR SLIDING MOVEMENT WITHIN SAID DRIVE CYLINDER, THE UPPER END OF SAID CYLINDER BEING OPEN TO ADMIT COMPRESSED GAS FROM SAID HIGH PRESSURE CHAMBER TO THE UPPER SIDE OF SAID DRIVE PISTON, A BLAST VALVE CLOSING SPRING BIASING SAID PISTON TO THE UPPER PART OF SAID CYLINDER, SAID DRIVE PISTON INCLUDING THEREIN A GUIDE CYLINDER WHICH MOVES WITH THE PISTON, AN ELONGATED MOVABLE CONTACT MEMBER INCLUDING AN INTERMEDIATE PISTON PORTION SLIDABLE WITHIN SAID GUIDE CYLINDER AND ALSO ACTUATABLE DOWNWARD BY SAID DRIVE PISTON, AN UPPER PORTION EXTENDING THROUGH THE UPPER END OF SAID HOLLOW DRIVE PISTON FOR ENGAGEMENT WITH SAID NOZZLE CONTACT MEMBER AND A LOWER CYLINDRICAL PORTION HAVING THE DUAL FUNCTION OF A DRIVE PISTON AND A VALVE SLEEVE, A BLAST VALVE SLEEVE UPSTANDING ON THE UPPER END OF SAID HOLLOW DRIVE PISTON AND SURROUNDING SAID MOVABLE CONTACT MEMBER, SAID BLAST VALVE SLEEVE BEING LOCATED WITHIN SAID HIGH PRESSURE CHAMBER AND BEING NORMALLY ENGAGED WITH A SEAT CLOSING OFF COMMUNICATION BETWEEN SAID HIGH PRESSURE CHAMBER AND THE JUNCTION BETWEEN SAID NORMALLY CLOSED STATIONARY AND MOVABLE CONACT MEMBERS, A GUIDE PIECE CONNECTED TO THE LOWER END OF SAID MAIN DRIVE CYLINDER, SAID GUIDE PIECE INCLUDING AN INLET SERVING TO INTRODUCE HIGH PRESSURE GAS INTO SAID MAIN DRIVE CYLINDER FOR FLOW THROUGH THE WALL APERTURE OF THE LATTER IN ORDER TO FILL SAID HIGH PRESSURE CHAMBER WITH COMPRESSED GAS AT HIGH PRESSURE, AND ALSO ALTERNATIVELY TO PLACE THE INTERIOR OF SAID MAIN DRIVE CYLINDER IN COMMUNICATION WITH A CHAMBER AT A LOWER PRESSURE, SAID GUIDE PIECE ALSO INCLUD-