GB694508A - Improvements in or relating to the repair of high tension insulated electric cables - Google Patents

Abstract

694,508. Cable joints. BRITISH INSULATED CALLENDER'S CABLES, Ltd. Sept. 21, 1951 [Sept. 22, 1950], No. 23306/50. Class 38 (i). A method of repairing a localised fault in a high tension cable having a lapped conductor dielectric comprises cutting out sufficient cable to ensire that the ends of the cut feeder are free of faulty dielectric, preparing each cable end as if to make a normal straight through joint and jointing the end of the core conductor of one cable end through an inserted length of unscreened insulated conductor to the core conductor of the other cable end, separately insulating the two longitudinally spaced joints, and enclosing them in a common casing. This method is simpler and requires less materials than the usual one of cutting out a few yards of the cable, making two straight through joints, and enclosing them in separate casings. Fig. 1 shows the left-hand half of a repair joint according to the invention as applied to a threecore 33 kv. solid type impregnated paper insulated cable. The damaged portion is cut out to leave the two cable lengths about 1 foot apart and the lead sheath 2 out back for about 20 inches, the cores 3 being spread out and a poultice 4 applied to seal the inter-core spaces. A lead stress cone 5 is fitted on each core 3 and the core screen 6 terminated thereat. The ends of the core conductors 7 are bared for some two inches and each is connected by soldered joints through a ferrule 11 to the bared end 10 of an inserted unscreened insulated conductor 8, the other end of which is similarly connected to the corresponding core conductor of the other cable end, Fig. 1A (not shown). The joints are wrapped with tapes 12, 13 and insulating paper tubes 14, 15, previously positioned on the inserted conductors 8, are slid thereover. The tubes 14, 15 are bound to pairs of spreaders 16 by tapes 17, the spreaders being supported in a pair of insulated yokes 18 prevented from angular movement by a bar 19, Fig. 2, carried by a spigot ring 20. The joint casing 21 comprises two similar end parts 23 and an intermediate part 22, which are connected to one another and to the spigot rings 20 by wiped metal joints 25. The end parts 23 are jointed through lead sleeves 26 and wiped joints 27 to the cable sheaths 2. The cut-back armouring wires 28 are secured by clamps 29 connected by bonding strips 30, the stress cones 5 being connected to the corresponding sheath 2 by wire 105. The casing 21 which is filled with compound is inserted in a concrete box 31 also compound filled. The inserted conductors 8 may comprise scrap lengths of cable cores or insulated copper rods, and the latter may be formed with sockets to receive the cable conductors.