GB942240A - Lightning arrester - Google Patents

Abstract

942,240. Lightning arresters. WESTING- HOUSE ELECTRIC CORPORATION. May 31, 1962 [Aug. 2, 1961], No. 21068/62. Heading H2H. [Also in Division H1] In a lightning arrester of conventional design, the ionized gas produced by the non-linear resistance blocks when the arrester develops a fault is used to establish an arc path in the arrester housing and so divert the fault current from the blocks, thus preventing further gas production and the build-up of excessive pressure. The arrester comprises an insulating housing 10 sealed by rupturable metal diaphragms 16 and having metal end fittings 12 provided with baffles 20. The housing 10 encloses two assemblies 22, 24, each comprising insulating tubes 26, 28, 30 arranged in cloverleaf formation between end caps 42. Each tube contains non-linear resistance blocks 34 and a spark gap device 32 comprising a plurality of electrodes in a sealed porcelain tube 36, the various elements in the three tubes being seriesconnected. The tubes 26, 28, 30 have openings 50, 52 at their mid-point, lower and upper ends respectively, and the free space in the housing 10 is filled with an electronegative gas such as sulphur hexafluoride. The circuit through the arrester is completed at each end by a current sensitive element contained in a tube 60 closed at one end by a projectile 62 held in place by the spring arms 66 of a strap 64. When the arrester developes a fault, the blocks 34 produce highly ionized gas which escapes through the openings 50, 52 and envelopes the assemblies 22, 24 to provide an arm path externally thereof. Subsequently, the current-sensitive elements vaporize and the pressure produced in tubes 60 causes the projectiles 62 to strike and rupture the diaphragms 16, thereby allowing gas to exhaust through the baffles 20 and establish an additional arc path exterior of the housing 10. The nature and arrangement of the elements in the tubes 26, 28, 30 may be varied as desired. U.S.A. Specification 2,858,476 is referred to.