GB252185A - Improvements in and relating to electric circuit controlling devices - Google Patents

Abstract

252,185. British Thomson-Houston Co., Ltd., (Assignees of Roberson, F.). May 16, 1925, [Convention date]. Automatic circuitbreakers. - High-speed circuit-breakers have a pair of co-operating independently - movable contact arms (each adapted to be held against an opening bias in the closed position) which are released on overload to break the circuit. In re-closing the two contact-members are moved in succession to their closed positions in which they are held by a single normally energized electromagnet so that release of the circuit-breaker is instantly effected if the overload persists when the circuit is again completed. As shown applied to circuit-breakers of the type described in Specification 125,279 the two pivoted contact arms 10, 11 carry armatures 18, 19 adapted to be held against pairs of poles 22, 24 of the retaining electromagnet 20 against the action of return springs 12, 13. The main circuit passes through conductors looped through the poles of the retaining magnet in such a manner that when an overload occurs the flux of this magnet is diverted from the armatures 18, 19, the contact arms being released to break the circuit at contacts 16, 17. In reclosing one of the contact arms e.g. 10 is first moved to its retained position by the manual or electromagnetic closing gear 23 after which the other contact arm 11 is similarly moved by its closing gear 25. If when the contact 17 re-engages contact 16 an excessive current flows, the contact arm 10 is instantly released and the circuit immediately re-opened.