GB1005039A - Arc-gap arrangement for lightning arresters - Google Patents

Abstract

1,005,039. Arc discharge tubes. HUBBARD & CO. April 13, 1961 [Jan. 19, 1961], No. 13317/61. Heading H1D. [Also in Division H2] An arc gap structure for a lightning arrester of the hermetically sealed type comprises a plurality of electrodes 22, 221 each forming a substantially U-shaped current path and separated from an adjacent electrode by insulating spacing means 40, each electrode having, on at last one arm of the current path, an initial arc portion 19, 21 and further arc portions 58 &c. and 15 &c., and a gas dispersion chamber or chambers 70 defined by the spacing means 40 and the electrodes 22, 22<SP>1</SP> adjacent thereto, adjacent electrodes being so arranged that the magnetic field set up by the passage of current along the substantially U-shaped paths moves the arcing path from passing between the initial arc portions 19, 21 to passing between the further arc portions, and hot gases are permitted to flow away from the arcing path through the dispersion chamber 70 in a direction substantially perpendicular to the direction of movement of the arc. The arc portions are formed by a single arc terminal 30, 32 of non-uniform depth, the terminal 30 on one arm of the electrode 22<SP>1</SP> projecting from the eleetrode in a direction opposite to that of the terminal 32 on the other arm and to that of the corresponding terminal 32 on the adjacent electrode 22. The terminals 30, 32 can be formed by indentations in the surface of the electrode and can be of skew truncated pyramidal form. In a modification each terminal can be a generally wedge-shaped indentation across substantially the entire width of each arm of the U-shaped electrode, the smallest surface of the wedge facing the curve of the electrode. The electrode spacing means 40 comprises a plate of insulating material, preferably non-organic, having holes 52 in alignment with pins 34 and holes 36 in the electrodes. In a modification the main surface of the electrode can be positioned in substantially the same plane as the top surface of the insulating plate, the only extending portion being the arc terminal. Each insulating plate 40 has two pairs of raised shoulder portions 42, one pair on each side, an electrode terminal aperture 46 having a ledge 48 and a plurality of slots 51 on each side of the plate. The electrodes 22, 21<SP>1</SP> and insulating plates 40 are assembled within a hermetically sealed housing 10 of porcelain to form a lightning arrester, one end 12 of which is connected to ground and the other end of which is connected by a conductor 14 to the equipment to be protected. A metallic member 18 is mounted between a conductive cap 16 and non-linear resistance material 26.