GB684868A - Improvements in automatic electric circuit-breakers - Google Patents

Abstract

684,868. Automatic circuit-breakers. MARCOZ, J. A. E. June 26,1950 [July 29, 1949], No. 15902/50. Class 38 (v) A trip-free circuitbreaker or switch has a pair of co-operating contacts 1, 2 mounted on spring blades 3, 4 normally biassed upwardly into the positions shown in Fig. 3. To close the switch, a push button 7 is depressed, the initial movement of the button moving a comparatively weak blade spring 6 down into engagement with the blade 3 and bringing a projection 11 of the button adjacent to the blade 4. As the downward movement of the button continues, the blades 6, 3 are moved until the blade 6 engages beneath a latch member 9. Just before the blades 6, 3 are latched, the projection 11 moves the blade 4 downwards, so that having latched the blade 3, it is necessary to release the button 7 before the contacts 1, 2 can be closed by the subsequent upward movement of the blade 4, thus rendering it impossible to hold the contacts closed under overload conditions. The latch member 9 is carried by a spring plate 10 connected by a insulated set screw 13 to a U-shaped bimetallic element 12. Distortion of the element 12 deflects the plate 10 to trip the switch. The direction of the current in the blades 3, 4 and the arms a, b of the element 12, Fig. 4, is such that the members 3, 4, a, b form a coil to blow out the arc formed between contacts 1, 2 when the switch is tripped.