GB635516A - Automatic electric circuit-breaker - Google Patents

Abstract

635,516. Automatic circuit breakers. BERTHIER, E. A. Dec. 24, 1947, No. 34242. Convention date, Feb. 16, 1944. [Class 38 (v)] The contact-carrying arm 14 of a circuitbreaker is normally held against the action of its mounting spring 16 by a roller 18 on the arm engaging a notch 37 in a latch 13 pivoted at 21 in a groove 23 in the resetting plunger 19. A U-shaped bimetal strip 9, connected in series in the controlled circuit, is mounted at 11 and carries at its free end 9a a knob 12 which, on overload, 'rocks the latch 13 and releases the arm 14, thereby opening the contacts 15, 36. In this operation the contact 15 strikes a pawl 26 pivoted at 30 thereby moving it to release the plunger 19 which is then pushed out by a spring (not shown), and the latch 13 is urged by its spring 24 to re-engage the roller 18. On depression of the plunger 19 a spring 25 acts on the pawl 26 to retain the breaker closed. The breaker can be manually tripped by pressing a button 28 which operates a lever 31 supported by the pivot 30 and adapted to move the pawl 26. The contact 36 is mounted on a magnetic core 35 having a winding 34 in series with the controlled circuit, the arrangement serving to blow out the arc. The resistance of the winding 34 serves to limit the short-circuit current and protect the bimetal strip 9. To permit the interrupting of larger currents, a number of contacts 41 ... 46 may be employed, Fig. 4, the " fixed " arcing contact 45 of carbon being controlled by a spring 47. In Fig. 7, a " fixed " contact 56, on each side of the arcing contacts 45, 46, is pivoted at 53 and is moved slightly upwards by a spring (not shown) when the contact 57 opens the circuit. This sliding movement between the contacts 56, 57 cleans their surfaces and the pressure between them is equalized by loosely mounting the contact 57 on the cam 14.