Improvements in or relating to lightning arresters comprising a gas discharge tube

摘要

803,890. Cold-cathode tubes. TELEFONAKTIEBOLAGET, L. M. ERICSSON. June 14, 1956 [June 14, 1955], No. 18476/56. Class 39(1). A gas discharge tube, intended for use as a lightning or surge voltage arrestor, comprises two electrodes 1 and 2, arranged to form a discharge path, and a bridge 6 extending along the length of the path and spaced from the electrodes 1 and 2 for reducing the ignition delay of the tube. The bridge is made of a composition including an electrically conductive material, such as aluminium, tantalum, titanium or zirconium in powder form, and a binder such as sodium or potassium silicate, which forms a thin insulating layer on the surface of each of the metal grains by a chemical reaction. The material used for the bridge should have a non-linear voltage/current characteristic. When a surge voltage with a steep front appears, there will be a great number of very small discharges between the metal grains in the bridge, so that ionization is produced simultaneously at all points in the discharge path, thereby reducing the ignition delay. A small quantity of radium may be added to the electrode material for the same purpose.