GB185514A - An automatic electric circuit breaker for equilibrated polyphase electric circuits - Google Patents

Abstract

185,514. Balducci, A. June 7, 1921. Automatic circuit-breakers for balanced polyphase circuits have a single tripping-coil 1 in one phase which actuates armatures in accordance with predetermined maximum and minimum values of current to interrupt all the phases. This interruption is effected by a multi-polar switch having bridging-contacts 13 secured on a spindle 12 with a crank 12<1>, the switch being closed by an operating-handle 14 with an arm 14<1> which, bv abutting against the crank 12, carries the switch to its closed position, in which it is retained against an opening-spring by a pivoted catch 9 pressed by a spring 17 to engage a recess 10 in a sector 11 on the shaft 12. The trip coil 1 has a core with pole-pieces 2, 2<1> and pivoted armatures 3, 3<1> for minimum and maximum interruption respectively. The former when allowed to drop owing to insufficient current in the coil 1 engages, by an arm 6, a collar 7 on a sliding rod 8, thereby releasing the catch 9 and allowing the switch to open the circuit. The armature 3, when attracted to the pole-piece 2<1> by reason of current above the predetermined maximum flowing in the the coil 1, depresses a rod 18, passing through the core. against the action of a spring 15. The rod 18 rocks a bellcrank lever 16 which in turn depresses the rod 8 and releases the catch 9, allowing the switch to open. In order to prevent attraction of the armature 3<1> on the initial rush of current arising when the switch is first closed, the handle 14 is provided with a hooked lever 4 engaging a similar lever 5 attached to the armature 3<1> the handle 14 being held in its final position until the current subsides to a normal value.