GB842902A - Improvements in and relating to electric circuit breakers - Google Patents

Abstract

842,902. Automatic circuit-breakers; mechanical switches. MECHANICAL PRODUCTS Inc. Feb. 12, 1957 [July 16, 1956], No. 4729/57. Class 38 (5). An automatic circuitbreaker has a spring- biased plunger 21, a member 57 supporting movable contacts 27 for lineal movement on the plunger, a spring-biased latch 73 pivoted on the member 57 and normally engaging the plunger 21 to connect the plunger and supporting member together for movement as a unit and thermal overload means 97 to move the latch 73 against its spring 77 out of engagement with the plunger. When the latch is released, springs 85 pull the member 57 down to open the contacts 25, 27. At the same time, the force exerted by the springs 85 on pivoted latches 93 is reduced, so that a spring 51 is able to force the plunger 21 downwardly, forcing rollers 109 of the latches 93 away from shoulders 111 of the plunger. The plunger then moves down to a position in which the latch 73 re-engages the end 65 of a slot in the plunger when the bimetallic element 97 cools. To reclose the circuit-breaker, a button 43 is pushed until the contacts reclose and the rollers 109 engage the shoulders 111 to latch the plunger 21. The circuit-breaker may be opened manually by pulling the plunger so as to cause the shoulders 111 to cam the rollers 109 into a position where the plunger is permitted to move to the " off " position. In a modified arrangement, Fig. 10, the plunger is in two parts connected together by a rivet and slot connection 145, 147. The plunger is normally latched by the rollers 137 abutting latch surfaces 151 on the part of the plunger to which the contacts are latched. When the button 153 is pulled, cam surfaces 149 on the other part, 141, of the plunger cam the rollers 137 away from the latch surfaces 151 to release the plunger. For ambient temperature compensation the bimetallic element may be formed in two parts, a current-carrying part and a reversely disposed non-current-carrying part, Fig. 9 (not shown).