GB1523375A - Surge arrester - Google Patents

Abstract

1523375 Spark-gaps MITSUBISHI MINING & CEMENT CO Ltd 12 Feb 1976 [22 Feb 1975 4 July 1975] 05629/76 Heading H1D A surge diverter comprises an insulating body 1 carrying two or more areas 2 of conducting thin film separated by narrow gaps 3 of 10-100 micron, each area 2 carrying an incorrodible conducting electrode 6 and the whole being sealed with insulating covering material 5 to enclose a gas between the electrodes. The film may be made from Ag paste or solder conducting paint, or Ag, Cu, Al or C film, the metals being vacuum deposited and the carbon cracked from hydrocarbon, e.g. benzene. The electrodes 6 made from one of Cu, Zn, Ni, Al, Fe or from brass, phosphor bronze or stainless steel carry soldered leads 8. The gas may be O 2 free such as Ar, He, Ne, Kr, N 2 , Cl 2 , H 2 , CO, CO 2 , SF 6 or a mixture, at any pressure, or O 2 containing gas such as air at sub-atmospheric pressure. The diverter is sealed in epoxy resin or a glass such as lead, soda, borosilicate or silica glass. The gaps separating the film areas may be made by laser or diamond scribing. Structures with three electrodes forming parallel centre-to-end paths (Fig. 3, not shown) and with the film areas on the outer periphery of a body (Fig. 7, not shown). The inter-electrode capacitance with 50 Ám. gaps between C films is of the order of 5 pF, and in atmospheric argon, when compared with atmospheric air, the spark-over voltage is reduced to 320V from 500V, the life on 3 kV. surges of (1 x 40) Á.sec. waveform is increased from 1000 to 1500 surges, time lag at 320 V is 1 Á.sec. falling to less than 0À1 Ásec. at 400 V., and in spite of a direct bias of 100 V., a 10A surge current is cut off without follow current. The results for the other example shown are similar.