GB1398857A - Electrical circuit breaker - Google Patents

Abstract

1398857 Automatic circuit breakers SIEMENS AG 31 July 1972 [31 July 1971] 35758/72 Heading H1N An electrical circuit breaker comprises a forked switch arm 7, Fig. 2, which, in the breaker open position of Fig. 1, has its extremities 7a, 7b, 7c pressed into stable three-point bearing engagement against guide portions 9, 10 of a housing 2 by means of a spring 8 secured between the switch arm and the housing. Two parallel lugs 12a, 12b of the switch arm 7 in planes mutually perpendicular to the pivotal axis of a rocker operating member 3 have arcuate guide surface edges 13a, 13b for sliding movement over guide portion 10 when the arm 7 is displaced against the action of spring 8 into the breaker closed position of Fig. 3 by anticlockwise movement of a handle 3a of the rocker member 3 which causes two arm portions 3b to rotate so that their arcuate edges 3c engage the upper surface of the switch arm 7. The displacement action is such that end 7c of the arm 7 becomes abuttingly engaged with a latch shaft 11, a first contact 14 carried by the arm 7 is movedinto engagement with a resiliently mounted fixed second contact 16, and the breaker is held closed by frictional engagement of the edges 3c bearing on grooved regions 17a, 17b of the switch arm 7 at a point on a perpendicular 20 drawn through the pivotal axis of the rocker arm 3. From this closed position the breaker can be opened to the Fig. 1 position either by clockwise movement of the handle 3a or it can be automatically released by means of an electromagnetic or thermal tripping device (not described) which is arranged to turn the latch shaft 11 in a clockwise direction whereupon the end 7c is unlatched and the arm 7 pivots around the edge 3c under the action of spring 8 with the guide surface edges 13a, 13b sliding along the guide portion 10 until it assumes the position shown in Fig. 4 from which it is restored to the Fig. 1 position by automatic resetting of the rocker member 3 by means of a torsion spring 5. In a modified embodiment (Figs. 5, 6, not shown) there are additional arm portions 7d to the switch arm 7 and 11c to the latch shaft 11 which coact with arms 27b and 27a respectively of a pivotable coupling shaft 27, axially parallel to the axes of rocker member 3 and latch shaft 11, which is coupled to a similar coupling shaft of an adjacent circuit breaker unit through an intermediate member 30.