GB835554A - Electric circuit breakers - Google Patents

Abstract

835,554. Automatic circuit-breakers; mechanical switches retained set; contact members for switches. MECHANICAL PRODUCTS Inc. June 4, 1956 [July 20, 1955; July 25, 1955], No. 17229/56. Class 38 (5). A circuit-breaker comprises a current-responsive thermal latch 28 operative to automatically release the movable contacts 20 for movement to open position only on the occurrence of overload, a manual actuator 38, 50 operatively connected with the movable contacts 20 and a mechanical latch 52, 52<SP>1</SP>, the actuator being effective on movement in one direction to close the contacts 16, 20 and actuate the mechanical latch to hold the contacts closed and on movement in the other direction to release the mechanical latch and open the contacts without releasing the thermal latch, and means movable with the movable contacts to release the mechanical latch when the contacts open on release of the thermal latch. Figs. 1, 2 and 8 show the circuit-breaker in the closed position in which an assembly comprising flexible contact-carrying arms 22, the thermal latch 28 and a saddle 118 are latched to the upper part 38 of the actuator by the engagement of the latch 28 with abutments 36 on the part 38, which in turn is latched by the engagement of the mechanical latch arms 52, 52<SP>1</SP> with fixed abutments 82. When the circuit-breaker is opened manually by pulling an actuating knob 54, a lost-motion connection 44, 46 permits the part 50 of the actuator to move relatively to the upper part 38 so that cam surfaces 51 on the part 50 spread the mechanical latch arms 52, 52<SP>1</SP> apart and disengage them from the abutments 82. Springs 96, 124 and 128 then open the contacts and force down the actuator. The circuit-breaker is reclosed by pushing in the knob 54 until the contacts close and the arms 52, 52<SP>1</SP> relatch on the abutments 82. When an overload occurs, the thermal latch 28 disengages from the abutments 36 so permitting the springs 96 to open the contacts. At the same time, the spring 124 forces down the saddle 118 so that it strikes flanges 120 extending from the actuating part 50. The resulting movement of the actuator part 50 releases the latch arms 52, 52<SP>1</SP> so that the actuator is forced down to its off position and permits the thermal latch 28 to re-engage the abutments 36 on cooling. Contact members for switches.-Instead of the movable contacts being mounted on the flexible arms 22, Fig. 1, they may be carried on rigid plates pivoted on extended portions of the latch 28, Fig. 15 (not shown), or on rigid plates 14b pivoted on rigid arms 18b, e.g. of stainless steel, welded to the latch 28, Fig. 19. The springs 96 are anchored to the plates 14b so as to cause the plates to pivot when the contacts are opened and closed so as to provide a wiping action. Fig. 19 also illustrates an arrangement having arcing contacts 48b, e.g. of tungsten, and current carrying contacts 46b, e.g. of silver cadmium oxide. Specification 756,764 is referred to.