ELECTRICAL CIRCUIT-BREAKER

1388599 Automatic circuit-breakers C M C CHARLES MAIER & CIE 27 Sept 1972 [30 Sept 1971] 44519/72 Heading H1N A circuit breaker has a bell-crank lever 3 and a further lever 2 pivoted on a common fixed spindle 1, one end of the lever 3 carrying a pivoted contact 4 and the other end of the lever 3 being linked by a pawl 8 to the lever 2. An operating handle 5 has a pin 7 engaged in a slot in the lever 2 so that clockwise motion of the handle closes the contacts 4, 11 against the bias of a spring 9. In the event of overload a bimetallic strip 24 moves a member 25 to disengage the pawl 8 from the lever 3 which is turned by the spring 9 to open the contacts. A spring (not shown) moves the handle 5 back to the off position to reset the pawl 8. Under short-circuit conditions an electromagnet 16 moves an armature 20 to turn a member 22 to move the member 25 to release the pawl 8 and at the same time moves a pin 21, which strikes the moving contact 4 to provide a rapid opening movement. Two levers 2 may be provided, one on each side of the lever 3 which may carry a bridging contact or two interconnected contacts which co-operate with two fixed contacts.