GB374708A - Improvements in or relating to electric circuit breakers - Google Patents

Abstract

374,708. Automatic circuit-breakers. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburg, U.S.A.- (Assignees of Dorfman, H. D. ; R. F. D. 4, Mansfield. Ohio. U.S.A.) Sept. 1. 1931, No. 24531. Convention date, Sept. 6, 1930. [Class 38 (v).] The latch arm 42 of a thermallv - released circuit - breaker is retained beneath surfaces of cams 34, 35 which are pivoted at 37 between the arms of a U-shaped bracket 31 and biased to a releasing position by a spring 41. Rotation of the cams to release the arm 42 is normally prevented by the engagement between noses 47 on the cams and projections 46 on bimetallic elements 44, 45 carrying the main current. If either or both elements 44, 45 deflects sufficiently due to an overload, the corresponding cam or both cams is released, allowing the arm 42 to rise and separate the contacts 26, 27. For resetting, the cams are provided with projections 43 which are engaged by the arm 42 to rotate the cams into their latched positions, in which the projections 43 overlap. The elements 44, 45 may be located one in each pole of a multi-pole switch. Switches, quick-action.-The arm 42 is formed as an extension of a cradle 9 which is pivoted at 11 and formed with an apex 24 serving as a pivot for one end of a toggle 17, 18, the other end of which is pivoted at 22 to the movable contact-arm 19, pivoted at 21. A dead-centre spring 15 is anchored between the knee-joint 16 and handle 12, pivoted at 14, such that clockwise rotation of the handle 12 moves the spring 15 over the line of centres 16, 24, thereby closing the switch with a snap action, provided the arm 42 is latched as shown in Fig. 1. The switch can similarly be opened manually by reverse movement of the handle, or automatically on overload by the spring 15 when the arm 42 is freed.