GB1282155A - Circuit breaker with improved trip means - Google Patents

Abstract

1282155 Automatic circuit breakers WESTINGHOUSE ELECTRIC CORP 8 Oct 1969 [24 Oct 1968 (2)] 49472/69 Heading H1N The tripping mechanism of an automatic circuit breaker comprises polepieces 131, 133; permanent magnets 139, 141, 142, 143; a fixed keeper 153 and a movable armature 163, the latter being coupled to an actuator 161; and coils 135, 137 bucking the permanent magnetic flux so as to divert the flux from the low reluctance path through the armature to the higher reluctance path through the fixed keeper, thus releasing the armature to trip the circuit breaker. The coils are energized by D.C. pulses, on overload, by a protective circuit (not shown). The keeper 153 is separated from the polepieces 131, 133 by an insulating sheet 155. The actuator 161 is coupled by a shock absorbing spring 171 and biased, to separate the armature and polepieces, by a spring 79; it is coupled to a tripping lever 187 having an extension 195 which acts on a first latch 63 of the circuit breaker; a resilient resetting lever 199 acts to return the armature when a bar 19 coupling the three sets of contacts 13 moves to the open position. Release of the first latch 63 releases a second latch 53 which is pushed aside by a pivoted member 45 allowing a toggle linkage 29, 31 to collapse upwards opening the contacts. The final movement acts to release an auxiliary latch 69 allowing a second toggle 33, 31 to collapse downwards, thus resetting the first toggle 29, 31 and the main latches ready for reclosure. Reclosure is brought about by turning a handle 113 on shaft 115; a crank 117 is rotated to pull the bottom end of a closing spring 83 upwards, its top end being restrained by a looked toggle 93, 97. The final movement of crank 117 acts to pull upwards a rod 105 slightly; this releases the toggle 93, 97 allowing the spring to drive the rod 105 rapidly upwards to re-engage the pin 39 with latch 69 and thus reclose the contacts. In an alternative embodiment (Figs. 8-19, not shown) a three phase circuit breaker is assembled between four parallel plates; two closing springs are mounted on opposite sides of the middle plates and coupled between fixed points on a cam-shaft arranged to operate the contacts from open to closed position on release of the springs. The springs are wound by rotating the cam-shaft.