GB784866A - Improvements in and relating to electric circuit breakers - Google Patents

Abstract

784,866. Automatic circuit-breakers; snap-action switches. IGRANIC ELECTRIC CO., Ltd. Sept. 16, 1954 [Oct. 16, 1953], No. 26877/54. Class 38 (5). A trip - free, snap - action switch for a motor starter comprises movable contacts mounted on a pair of bridges 42, urged to contact-closed position by springs 48, sliding on an insulating contact carrier 46, itself guided in groove 18 and slots 38 in the base 10. A contact operating lever 82 has a finger 84 slidable in slots 20 in the base and engaged with slot 50 in the contact carrier 46, the lever being actuated manually by an over-centre spring action comprising a lever 52 and a spring 76 secured to the bridge of a support 70, pivoted to lever 52 by a pin 74, and to a hole 78 in a yoke 62 which is pivoted between trunnions 56 of the lever 52 by a pin 64, a slot 80 allowing yoke 62 to swing about pin 74. As lever 52 is swung from " on " to " off " (Fig. 2), pin 64 moves anti-clockwise about pivot 74 until pin 64, hole 78, and spring 76 are in alignment, and the spring support 70 initially held against a groove 32, and when alignment position is passed, the legs of the spring support 70 will contact lever 82 and swing it to the position shown in Fig. 2, finger 84 thus depressing the contact carrier 46 and opening the contacts. On overload, the heater coil of a thermal release assembly melts a blob of solder allowing a ratchet 106 to rotate and release a spring finger of an arm 102 forming part of lever 90 pivoted on pin 74 which then rotates under influence of a spring 98, the lever 102 engaging a bar 88 on lever 82 and thus opening the contacts (Fig. 4). To reset the switch, the lever 52 is swung from the " on " (Fig. 4) to the " off " position, which causes the lower left-hand edge of the lever to engage the bridge of lever 90 and swing it anticlockwise to carry arm 102 to the position of Fig. 2 so that finger 104 again engages with ratchet 106.