GB532303A - Extinguishing chamber with differential piston for electric circuit breakers - Google Patents

Abstract

532,303. Liquid-blast switches. RONNBERG, D., and ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET. Aug. 25, 1939, No. 24524. [Class 38 (v)] In order to prevent discharge between the opened movable contact 28 and parts in conductive connection with the fixed contact 1 in a differential - piston type of quenching- chamber, the parts are so arranged that re-striking of the arc will occur between the contacts, as in originally opening the circuit, the arc being then dealt with in the normal way by the blast. The piston comprises metal cylinders 8, 9 fastened to insulating caps 6, 7 which are separated by a space 15. The collar of 9 slides on an inner cylinder 4 connected by fins 3 to a guide sleeve 24 slidable on the rod 2. When an arc is struck, piston 6 ... 9 descends and simultaneously cylinder 4 rises, thus squeezing liquid from the space between cylinders 4, 8 and forcing it on to the arc as the contact 28 clears the openings 16, 17. This form is suitable for incorporating in a close-fitting cylindrical insulator in which descent of piston 6 ... 9 necessitates escape of the external displaced liquid through the constricted space round the chamber. Since the upward movement of 4 enables adequate blast to be got with a reduced vertical descent of the piston, the resistance to movement of the latter is reduced. When the chamber is inverted at the bottom of the container the cylinder 4 is fixed. Valves 12 enable the piston to begin to move before the holes 16, 17 are uncovered, and also permit closure of the contacts, and valves 23 allow the arc-gases to escape. The cavity 18 is for retarding the collapse of pressure when the holes 16, 17 are uncovered.