GB757088A - Improvements relating to automatic electric circuit breakers - Google Patents

Abstract

757,088. Automatic circuit-breakers. DORMAN & SMITH, Ltd. June 18, 1954 [July 10, 1953], No. 19180/53. Class 38(5) A dolly 10 pivoted between arms 8 of a frame 7 is connected by a link 11 to a movable contact 6 biased upwardly by a spring 16, so that when the switch is open a transverse pin 14 on the contact, guided in grooves 15 in the switch housing 4, engages arms 9 of the frame 7. A pin 12 in the link 11 co-operates with a flattened L-shaped slot 13 in the contact 6, the slot 13 providing, at its upper end, a shoulder on which the pin 12 is normally held by a hook 18 pivoted at 19, whereby when the dolly is turned clockwise to close the contacts 5, 6 the contact 6 first pivots on its pin 14 about the arms 9 until it engages the contact 5, further movement of the dolly to its final position forcing the pin 14 down the grooves 15, the contact 6 performing a rolling and sliding movement on the contact 5. The contacts may be. tripped open on overload by an armature 22 pivoted at 24 and having a tail 21 which engages a tail 20 of the hook 18 when the magnet core 23 attracts the armature, the pin 12 moving to the bottom of the slot 13 and permitting the spring 16 to open the contacts. The dolly is returned to the "off" position by a spring (not shown) whereby the pin 12 is reset on the slot shoulder. The breaker may be alternatively opened by hand. In a modification, the pin 14 is fixed to the housing 4 instead of to the contact 6 and co-operates with a slot formed in the contact.