GB540349A - Improvements in electric circuit breakers of the gas blast type - Google Patents

Abstract

540,349. Gas-blast switches. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 2, 1940, No. 13749. Convention date, Sept. 1, 1939. [Class 38 (v)] A gas-blast circuit-breaker, comprising a tubular contact 17 movable with a close fit within an insulating, gas - evolving liner 13 to engage a fixed contact 14, is adapted to interrupt a wide range of currents by providing an insulating extension 18 which is threaded into the end of contact 17 and has on its surface a number of longitudinal grooves 19 as shown or (Fig. 3, not shown) helical grooves, all communicating with a header or passage 20 in the region of contact-separation. When breaking large currents, the grooves cause the formation of a number of parallel-connected arcs, and the arc-gases evolved are transferred by way of passage 20 to other grooves. The cross-section of the latter may increase upwards or downwards according as to whether relatively small or large currents are to be dealt with. The liner 13 is held within an insulating cylinder 10 by a threaded member 14a and annular insulating washer 15 which is gripped between the two parts of a conducting housing 12 serving with strips 15 to lead current to contact 14. The liner and cylinder 10 are apertured at 21 t) pass the gas through inter-communicating exhaust chambers 23, 24 provided with wiremesh mufflers 27 and leading through openings 28 to atmosphere. Specification 463,411 is referred to.