GB1192897A - Molecular Sieve for Vacuum Circuit Interrupter - Google Patents

Abstract

1,192,897. Vacuum switches; gettering. WESTINGHOUSE ELECTRIC CORP. 21 Feb., 1969 [13 March, 1968], No. 9500/69. Headings H1D and H1N. A molecular sieve material 64 is contained within the evacuated envelope of a vacuum switch to absorb any gases or particles produced during arcing or leaking into the envelope. Suggested materials are the zeolites (aluminosilicates); activated carbon or charcoal; activated alumina; silica gel; certain reforming catalysts such as platinum on alumina; sintered porous-metals such as are used for filters; and metallic felt. These materials are more effective at low temperatures and therefore may be cooled by flowing liquid 97 such as liquid ammonia, nitrogen or the inert gases of Group O or by solid carbon dioxide. The vacuum switch comprises a metal envelope 44, insulated from a moving contact member 16 by a tubular insulator 32 and from a fixed contact member 12 by an insulating seal 45; the moving contact is sealed to a metal end plate 24 by a bellows 20. Supported with the envelope is a shield 50 surrounded by a jacket 68 containing the liquid coolant; which is also supplied to the hollow interiors of the contacts. Inside the shield 50 is a gauze screen 11 containing lumps or pellets 64 of the molecular sieve material. The irregular form is adapted to trap particles and prevent reflection of radiation back into the arc. The gauze 11 may be corrugated (Fig. 3, not shown), to further increase the irregularity. In a modification (Fig. 4, not shown), the molecular sieve material is located outside the cooling jacket 68 and therefore only serves to absorb the gas particles. The liquid cooling arrangements may be omitted (Figs. 2, 5, not shown), and the invention may be applied to a vacuum switch having a liquid gallium contact (153) (Fig. 6, not shown).