GB1373265A - Electric switching device - Google Patents

Abstract

1373265 Liquid-blast switches ALLMANNA SVENSKA ELEKTRISKA AB 21 Feb 1972 [22 Feb 1971] 7875/72 Heading H1N [Also in Division C3] An electric switching device is characterized by the fact that at least some electrically insulating part thereof which may be subject to arcing, comprises a fibre reinforced binder, in which the fibre reinforcement comprises polyvinylalcohol fibres or acetalized polyvinylalcohol fibres. The figure depicts a high voltage circuit breaker filled with liquid and having an extinguishing chamber. The extinguishing chamber 1 has a cylinder 2 concentric with it, both made of glass fibre reinforced plastics material. At the upper end is a metal cover 3 provided with a terminal 4 and stationary contact 5. The movable contact 6 comprises a contact plug which can be displaced into a current collector 7 by drawing through an arcing chamber 8. Extinguishing chamber plates 9 are arranged one on top of the other, in the chamber 8, and are reinforced as required by the invention. Each has a hole 12 through which contact 6 passes and also has a radially extending groove 10 in its upper surface (the plates touch out of the plane of the drawing) extending from hole 12 to an exhaust channel 11. The plates are thicker on the exhaust channel side than on the arcing chamber side. The grooves provide an escape for the arcing in chamber 8. A cylindrical screen 17 of the reinforced insulation of the invention is provided in channel 11 to protect its walls from the hot gases blown out of the grooves 10. The liquid is preferably oil which vaporizes during an arcing process and arcing to the escape through grooves 10, produces a flow of oil and gas, which produces a cooling effect. The binders for the fibres are synthetic resins such as (a) an unsaturated polyester cured with a methacrylate or acrylate ester monomer; (b) a cured mixture of a linear polyacrylate or polymethacrylate and a polyethylene glycol dimethacrylate or acrylate; (c) as in (b) contain also an unsaturated polyester, a diallyl phthalate or diallyl moleate prepolymer or an expoxy resin containing unsaturated groups; (d) a cured melamine-formaldehyde resin, or (e) a cured epoxy resin.