Improvements in Electric Circuit Breaker With Current-Limiting Arc Extinguishing Means.

摘要

1,196,798. Arc extinguishing in switches. GENERAL ELECTRIC CO. 6 Nov., 1967 [7 Nov., 1966], No. 50250/67. Heading H1N. An electric circuit interrupter has a contact chamber 14A from which the arc is blown into an extinguishing chamber 14B through a constricted passageway which is stated to prevent cavitation and consequent retrogression of the arc. The constriction (Fig. 2) is afforded by shaped side plates 18, 20 of gas evolving material, which may be an acetal resin such as polyoxy. methylene. These plates 18, 20 together with arc runners 22, 24 carrying fixed contacts 25 are supported between moulded insulating walls 10A, 10B clamped together by bolts 63; the walls 10 may be of glass fibre reinforced alkyd resin or polymer. The tips of arc runners 22, 24, where the arc becomes stationary adjacent perforated insulating wall portions 46, 48, are provided with tungsten carbide inserts 30, 32. A silencer 12 is fitted over the outlets of the perforations 50. Conducting splitter plates are omitted from the chamber to reduce current chopping and a glass-melamine strip 58 is placed between the inserts 30, 32 to dissipate the recovery voltage peak when the arc is extinguished; the strip 58 apparently becomes conducting in the presence of the arc. Connections 26, 28 are made to the contacts 25 in a manner such as to produce a strong magnetic blow-out field (Fig. 3, not shown). The bridging contact 36-38 is operated by overcentre mechanism through a releasable coupling as described in Specification 1,140,612, the coupling being released upon short circuit by an electromagnet acting directly on the contact rod 42 (Fig. 3A, not shown). The overcentre mechanism is releasable to open the contacts open lesser overloads by a bimetal 104 and electromagnetic trip 106.