GB911934A - Electric circuit breaker - Google Patents

Abstract

911,934. Automatic circuit-breakers. WESTINGHOUSE ELECTRIC CORPORATION. Jan. 11, 1961 [Feb. 15, 1960], No. 1184/61. Class 38 (5). In a circuit-breaker having both thermal and magnetic tripping means the thermal tripping means includes a bimetal having one portion which is movable on heating to release the operating mechanism and a second portion arranged to receive heat produced as a function of the current in a substantially straight conductor in series with the circuit-breaker. In a circuit-breaker generally similar to that described in Specification 886,267, each pole has terminals 15, 17 and is enclosed in a housing 11 and cover 13. The snap-action operating mechanism 27 controls main and arcing contacts 21, 23 and 22, 24 and includes a releasable cradle 63 normally held by a latch mechanism 93 controlled by a trip mechanism 29 through which the substantially straight conductor 43 passes. As shown in Fig. 4, the conductor 43 may be laminated and have the bimetal 155 secured thereto by rivets 157 so that its free end can act on a trip-bar (not shown) to release the latch mechanism 93. In alternative arrangements (Figs. 6 and 8), the straight conductor 161, 169 is recessed in the vicinity of the bimetal 165, 173 to increase the heating and this effect is also increased by the provision of additional corners and edges. As shown in Fig. 9, the constructor may comprise two parts 177, 179 with the end of the bimetal 181 secured between them. For heavy-current circuit-breakers the bimetal 191 (Fig. 12) is secured to and receives the heat from a core 193 surrounding a straight conductor 183. Non-magnetic shims 199 may be inserted to reduce the magnetic heating of the core 193.