GB1080623A - Improvements in or relating to protective spark gaps - Google Patents

Abstract

1,080,623. Protective spark gap arrangements. ENGLISH ELECTRIC CO. Ltd. July 12, 1965 [July 14, 1964], No. 28923/64. Heading H2H. A protective spark gap arrangement for a D.C. power line comprises a trigatron 11 having carbon main electrodes 15, 16 respectively connected to the line 13 and earth 14, which electrodes carry insulated trigger electrodes 19, 20 respectively connected to tappings 25, 26 on resistors 23, 24 in series with a spark gap 22 between the line and earth. In operation a predetermined surge voltage breaks down the gap 22 thereby causing each trigger electrode 19, 20 to spark over to its corresponding main electrode 15, 16 and so break down the gap 21 between these two electrodes to discharge the line voltage. The gap 22 is mounted in a sealed porcelain housing with or without the resistors 23, 24 one or other of which may be omitted in which case the trigger electrodes may be connected to tappings on the single resistor. One or other of the trigger electrodes may be omitted and the gap 22 may comprise multiple gaps in series. The sparking end of the trigger electrode may lie flush with the surface of the main electrode or be withdrawn within the body thereof. Each trigger electrode comprises a tungsten rod and the method of mounting this rod in the main electrode, Fig. 2 (not shown) comprises securing its lower end by a collet chuck 32 screwed into an insulating bushing 30 mounted in the electrode 16, and surrounding its upper (sparking) end by a ceramic sleeve 33. The electrodes 19, 20 are coaxial with the line joining the centres of the main electrodes 15, 16 which may be of any shape and disposition producing a uniform electric field in the gap 21, through which air may be blown to keep the electrodes free from dust.