GB700491A - Arrangement in air-blast electric circuit breakers provided with damping resistances - Google Patents

Abstract

700,491. Air-blast circuit-breakers. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET. Feb. 8, 1952 [Feb. 9, 1951], No. 3346/52. Class 38(5) A breaker comprises a fixed contact 3 and a tubular movable contact 6 which are bridged by a damping resistance 11 connected in circuit by a contact pair 14, 15 shortly after an exhaust valve 19, 20 is opened, and disconnected just before the valve is reclosed. The contacts are arranged in a compressed-gas container 1, contacts 6, 15 being mounted on pistons 8. 16, respectively, working in cylinders 9, 17. To open contacts 3, 6, a pushbutton 23 is pressed to de-energize a polarized relay 26 whose armature is forced up by a spring 27 so that a push rod 30 acts on a plate 33 to close the outlet from a valve 32 and to connect an air source 35 to a pipe 34. A piston 36 is thus raised and through a pivoted stem 40 changes over a disc valve 43, so that the space to the right of piston 16 is opened to atmosphere over pipe 45, and pipe 44 is closed. Thus air from the container flowing to the left-hand face of piston 16 through channels 53 causes the piston to move to the right. At the same time as the piston 36 moves up, a cylinder 46 is connected to the pipe 34 over a needle valve 57, and a valve 48 is changed over to close a second vent from pipe 44 and to open the space to the-left of piston 8 to atmosphere over a pipe 52. The piston 8 is thus moved to the left by the gas in container 1 and the arc between the contacts is blown out through the tubular contact 6, the blast exhausting through the valve 19, 20 which opens when the piston 16 is moved to the right to close the contacts 14, 15. After a certain time, a piston 58 is moved to the left by the pressure in cylinder 46 and deflects the stem 40 to the left against a spring 60, thereby allowing valve 43 to be moved back to the position shown by a spring 61 and connect the pipe 44 to the right-hand side of piston 16 so as to open the contacts 14, 15 and close valve 19, 20, the movement of the piston being delayed by the passage of air through channels 53, so that any arc formed can be extinguished by a blast through contact 15, openings 62 and the valve 19, 20. The breaker is reclosed by pressing a push-button 23<SP>1</SP> to energize a coil 63 and lift a valve 66 so as to connect the source 35 to a cylinder 28 over a pipe 67. The rod 30 is thus lowered. to allow a spring 311 to restore valve 33 to vent the lower side of piston 36, cylinder 46 and pipe 47 being vented first through pipe 34 and then through the space around stem 40. The breaker may have two main gaps each with a damping resistance, in which case the contact tube 15 has a forked end so as to co-operate with two contacts 14.