GB232808A - Electric switches - Google Patents

Abstract

232,808. British Thomson-Houston Co., Ltd., (General Electric Co.). June 4, 1924. High-potential switches for distribution &c. circuits have contacts separable in a polyatomic gas of high dielectric strength and good heat conductivity, such as chlorine or hydrogen. As shown in Fig. 1 a switch has fixed contacts 7, 8 bridged by a movable contact-member 12 attached by a rod 13 to the core of an operating solenoid 15. The switch contacts are mounted within a gas-tight chamber 1 provided with pipe connections 2, 3 for removing the air within the chamber and substituting gas at the desired pressure. In a modified form shown in Fig. 2 the chamber consists of a metal cylinder 22 with end covers 23, 24 through which pass insulators 26 carrying the fixed contacts 28. The movable switch contacts 33 are operated by a double lazytongs device 41 which is connected bv a rod 40 to the core 39 mounted within the operating solenoids 35, 36. The chamber has an insulating lining 25. To assist the re-combustion of the atomic hydrogen or other gas formed during the arcing at the contacts which occurs on interrupting the circuit through the switch, catalysing members 45, 46 are mounted adjacent to the contacts, these members being formed of tungsten, ground quartz or other suitable materials. Instead of providing separate catylysing members the lining 25 may be formed of catalytic material. Pipe connections 30, 31 are provided for scavenging the switch chamber of air and filling it with gas, which may be maintained at a pressure of several atmospheres. In order to extract oxygen and water-vapour from the gas suitable agents may be placed within the switch chamber. In a further modification the gastight chamber is formed of two open-ended casings bolted together the lower of which is partially filled with a sealing liquid into which projects the upper open end of the upper casing, so that before gas leakage can take place the ejection of the liquid provides a visible indication of the faulty joint between the casings. The switch chamber in this form is connected to a gas-filled cushion tank to relieve the high pressures incident on the interruption of the circuit.