GB886267A - Electric circuit breakers embodying electromagnetic release means - Google Patents

Abstract

886,267. Automatic circuit-breakers. WESTINGHOUSE ELECTRIC CORPORATION. June 8, 1960 [June 10, 1959], No. 20089/60. Class 38 (5). To set the instantaneous tripping current of a circuit-breaker having electromagnetic tripping means, the position of the armature 99 relative to the yoke 95 is adjusted by a pivoted lever 119 having calibrating means, e.g. a screw 135, at one end engaging the armature 99. The other end 129 of the lever 119 engages a face cam 121 carried by a shaft 143 rotatable in brackets 139, 141 which prevent axial movement of the shaft and cam. An adjusting knob 142 on the shaft 143 has a notched flange 144 biased against the bracket 141 by a spring 149 between the knob and the shaft, the notches 151 co-operating with a detent 153 to index the knob, shaft and cam. The armature 99 has a pivot 101 bearing in a notch 102 on one leg of the yoke 95, the other leg of the yoke having its outer laminations extended to form auxiliary polepieces 115 which, when the electromagnet is energized provide a backward pull on the armature. By turning the knob 142, the cam 121 causes the lever 119 to pivot and move the free end of the armature away from the auxiliary polepieces 115 and nearer to the yoke 95 to reduce the current setting. When the armature is attracted to the yoke 95 under heavy overload conditions, the head 105 of a rod 103 secured to the armature 99, engages and turns a pivoted trip bar 81 so that a latch 91 on the trip bar releases the circuit-breaker latch mechanism 93. Under smaller overload conditions, the trip-bar 81 may be operated by a bimetallic strip 45 which engages a calibrating screw 109 in the trip bar 81. A terminal strip 17 forms the winding for the electromagnet and the heater for the bimetallic strip.