GB673312A - Improvements in air-blast electric circuit-breakers with switching resistances - Google Patents

Abstract

673,312. Air-blast circuit-breakers. FORGES ET ATELIERS DE CONSTRUCTIONS ELECTRIQUES DE JEUMONT. July 28, 1950. [Aug. 2, 1949] No. 18880/50. Class 38 (v). A circuit-breaker has two contacts 14, 18 movable about a common pivot 17, the contact 18 separating first from its fixed contact 19 without forming an arc, followed by separation of the contact 14 from a tubular fixed contact 13 to form an arc in parallel with a resistance 24, this arc being extended through a nozzle 9 where it is extinguished by the air-blast, a further arc in series with the resistance being formed when the contact 14 separates from a second tubular, fixed contact 15. The contact 14 then moves to a position 14<SP>1</SP> to form an isolating gap and to give a visible indication that the circuit is open. The contacts are operated by a mechanism 21 which may be a fluid piston and which has a cam 31 acting through levers 29, 30 to open a valve 2, which is reclosed before extinction of the second arc which is blown out by residual pressure in the contact chamber. Contact 13 is mounted in the centre of an electrode 11 carried by a metal collar 6 and having an arcing tip 12 of refractory metal, the nozzle mounting 8 being separated from collar 6 by an insulator 7. In a modification, Fig. 3 (not shown), all of the parts are mounted on a single insulator supported by the air container 1, and in a further arrangement, Fig. 4 (not shown), the contact 15 is on the outlet side of nozzle 9 so that contact 14 passes through the nozzle. The contacts 18, 19 which short-circuit the breaker, may be omitted, and the circuit-breaker may be arranged with all its live parts in front of a partition, Fig. 2 (not shown).