DE1490048

1,038,326. Fluid blast switches. MASCHINENFABRIK OERLIKON. Nov. 17, 1964 [Sept. 9, 1964], No. 46691/64. Heading H2B. In a circuit breaker of the kind having an arc control chamber 3 into which arc quenching fluid is injected, during opening of the contacts 5, 6, by means of a piston 7 coupled to the movable contact 6, the piston 7 is arranged to draw fluid from a supply chamber 1, through valve 19 and opening 18, into a reservoir during contact closing and to discharge it therefrom, through a second valve 20, into the chamber 3 during contact opening. The fluid flows through turbulator 4 into a cowl 11 from whence it is returned to chamber 1 through normally open valves 15, 16 which close in the event of excessive pressure to prevent damage to insulator column 10. The upper side of piston 7 is returned to the chamber 1 by way of passages 21, 22; the piston 7 is spaced from the walls of its cylinder 8 so as to allow escape of fluid around the piston if, due to excessive pressure in the chamber 3, the valve 20 should fail to open.