GB365527A - Improvements in or relating to overload circuit breakers - Google Patents

Abstract

365,527. Automatic circuit-breakers. WEST & CO., Ltd., A., Lewes Road, and PAVITT, F. J., 19B, Madeira Place, both in Brighton. Oct. 17, 1930, No. 31115. [Class 38 (v).] An automatic circuit - breaker with thermal release comprises a springy movable contact arm 2 (Fig. 1) which is held in the closed position by an insulating roller 16 mounted on the common pivot 15 of a toggle-link 13 and a connecting link 14, the link 13 being pivoted at 17 to the inner portion 12a of an operating member 12 on a fixed pivot 11 and the link 14 being pivoted at 18 to a tripping arm 10. The tripping arm 10 is also pivoted at 11 and has a recess 9 normally engaged by a cross-bar 7 of an arm 8 pivoted at 7a, the free end of the arm 8 being held normally by a bimetallic strip 6 carrying the controlled current. When the strip 6 is deflected owing to excessive current it releases the arm 8 so that the circuit-breaker is opened by the spring action of the contact arm 2, the parts assuming the position shown in Fig. 5. To reclose the switch, the handle is returned to the " off " position during which the pivot 17 engages the extension 20 of the tripping arm 10 and swings it and the bar 8 to their original positions. If now the bimetallic strip has cooled sufficiently the arm 8 is retained and in turn retains the tripping arm 10 so that if the operating member is then moved to the " on " position shown in Fig. 1, the toggle members 12 and 13 can force the contacts into engagement, the arm 12a and link 13 thus forming an overset toggle held by the pivot 17 engaging the arm 10. An adjustment of the tripping current is provided (Fig. 3) by mounting the arm 8 on an eccentric pivot which by rotation, as indicated by a fixed pointer 20 on a scale 21, varies the longitudinal position of the arm 8. The switch is provided with blow-out coils of the type described in Specification 175,663, [Class 38 (v), Electric switches &c.].