GB921420A - Improved electric circuit breaker and latch structure - Google Patents

Abstract

921,420. Automatic circuit-breakers; camoperated switches. HEINEMANN ELECTRIC CO. June 8, 1959 [March 18, 1959], No. 19591/59. Class 38 (5). In an automatic circuit-breaker a force transmitting linkage between an operating member and a biased moving contact member comprises a pair of relatively pivotable links associated with a bowed spring. As shown, the links 73, 74 are normally retained by the bowed spring 71 in substantial alignment against a wall 90 along which the link and spring assembly can slide to transmit force from the operating handle cam 54 to the laminated contact spring 35 which is biased away from the fixed contact 30. The outer ends 76, 76<SP>1</SP> of the links 73, 74 retain the ends 85, 85<SP>1</SP> of the bowed spring 71 and are guided for straight-line movement in slots 77, 78 in a two-part casing having other slots and recesses for locating circuit-breaker parts and from which the wall 90 projects. On overload, a series electromagnet 37, 43 attracts an armature 45 which is pivoted at 47 and has a limb 49 which moves through a gap 91 in the wall 90 to engage the link 73 so as to move the spring 71 over-centre so that the links are no longer in force transmitting alignment and allow contact 35 to move away from the fixed contact 30. Since the end 76 of the link 73 is no longer urged into a notch in the cam handle 54, the latter is restored to the " off " position by a spring 64 mounted about its pivot 56. The spring 71 is unstable in its bowed upward position and acts to reset the links 73, 74 in substantial alignment.