GB783263A - Improvements in or relating to electric arc converters - Google Patents

Abstract

783,263. Metal-vapour converters. GENERAL ELECTRIC CO., Ltd., HOLLIDAY, J. H., and MACHIN, C. F. Feb. 25, 1955 [March 24, 1954], No. 8602/54. Class 39(1). An anode arrangement for a high voltage electric arc converter comprises an anode supported concentrically within, and insulated from, a surrounding conducting part such as a metal shield, the anode having a hemispherical free end whose diameter is approximately equal to one half the diameter of the said surrounding conducting part. The mercury arc rectifier shown comprises a tubular metal part 1 consisting of an upper portion IA and a lower portion 1B brazed together. The portion 1A carries a glass member 4 having a portion 6 sealed to a metal cup 7 carrying a terminal 8 and a stud 9 supporting the anode 5. The portion 1B has a flange 2 which is brazed to a cathode supporting member 3. A cap member 10 screwed onto the stud 9 carries a threaded spigot 11 bored axially for a screw 12. The anode 5 which is made of graphite and has a hemispherical end merging into a stem part, is screwed onto the spigot 11. A metal member 13 flared outwardly from a diameter equal to that of the stem part of the anode 5 is welded or brazed to the periphery of the cap member 10 and acts as a shield for the joint between the cup 7 and the glass portion 6. A metallic shield 14 serving to protect the joint between the metal part 1A and the glass member 4 is supported from the metal part 1B and carries an insulated grid 16 provided with a terminal device 17. The grid 16 consists of a plurality of concentric slats 18 the tops of which are spaced from the anode 5 at a distance equal approximately to the radius of the anode end. The diameter of the anode end is made approximately equal to half the diameter of the shield 14 at the position where the shield surrounds the free end of the anode, and the diameter of the stem part of the anode and of the adjacent end of the shield 13 are made approximately equal to 1/e times the reduced diameter at the top of the shield 14 where it is turned into a rim 15, the radius of curvature of which is suitably chosen with respect to the radius of curvature of the flared portion of the shield 13. The cathode assembly, which forms the subject matter of Specification 783,264, comprises a member 19 brazed to the member 3 and sealed to a glass pot 20 containing an annular mercury cathode pool 21 provided with a terminal rod 22. An auxiliary anode 23 is supported by a stem 25, and a baffle 24 is secured above the pot 20. A plurality of identical anode arrangements as described may be used in a polyphase converter.