GB721300A - Improvements in automatic electric switches having overload release means - Google Patents

Abstract

721,300. Automatic circuit-breakers. LEYHAUSEN, W. March 19, 1952, No. 7064/52. Class 38 (5). An automatic switch comprises a rectangular base 1, a contact chamber 3, a magnet coil 7 at the side of the contact chamber, thermal overload release means including a bimetal strip 9, the chamber, coil and strip being arranged in the space below that within which the switch actuating mechanism alone is located. In the Figs., the contact chamber 3 and a combined blow-out and overload release coil 7, Fig. 2, are carried in an inverted U-shaped frame 2 and the actuating mechanism is carried in an upright U-shaped frame 14, the bases 12, 13 of the frames being secured together. The chamber 3, Fig. 9, houses fixed contacts 4, 5 and a moving bridging contact 6, the chamber having arc cooling ribs 38 and vent apertures 37. The coil 7, with its core 48, is supported by a member 50 with projecting portions 51, 52, Fig. 1, which co-operate with the bifurcated limb 54 of the lower frame to positively locate the coil assembly. The actuating mechanism comprises an .operating lever 68, Fig. 25, with a forked member 66 carrying a pin 72 which engages a pivoted lever 73. An overset toggle 77, 79 is connected between the lever 73 and a bell crank lever 45 biased by a spring 91, Fig. 1, and connected to the moving contact 6 by a bar 43, Fig. 9. In the event of a severe overload the coil 7 attracts an armature 8 so that an extended portion 65 of the armature strikes a lug 81 on the toggle link 77. The toggle 77, 79 collapses and the spring 91 turns the lever 45 to open the contacts. In the event of a smaller overload, the bimetallic strip 9 bends and pivots a pawl 99 to release a lever 95. The lever 95 is pulled upwardly by a spring (not shown) and a projecting part 98 of the lever collapses the toggle 77, 79 to open the contacts. It is stated that when the switch is tripped, the direction of the pressure which the link 77 exerts on the lever 73 changes from that exerted when the toggle is in the dead centre position so that the lever 73 can turn the lever 68 to reset the switch. In a modification, Figs. 26, 27 (not shown), the lower part of a housing is divided into three compartments containing respectively the contacts, the coil, and the armature together with the bimetallic strip. The upper part of the housing is separated from the lower part by a partition and contains the actuating mechanism which is operated by a push-button. A further push-button is provided for manual tripping of the linkage.