Patent GB-1242068-A (GB)
Title: Cable termination for use in grounded surface distribution apparatus
IPC: H02G15/10
Filed: 1968-07-02
Abstract: 1,242,068. Electric couplings; fusible cutouts; protective arrangements. JOSLYN MFG. & SUPPLY CO. 2 July, 1968 [15 Aug., 1967], No. 31485/68. Headings H2E, H2G, and H2H. In an underground high-voltage distribution system, cable ends are terminated in a manner which enables them to be used with a plurality of interchangeable devices for jointing, endstopping, fusing, tapping, and load-breaking purposes. As shown, Fig. 2, the cut-back end of a high-voltage cable 45 is sealed into one end of a conductive housing 34, of e.g. stainless steel, by a soft dielectric filler 38, e.g. polyurethane, which is sealed around the cable insulation 46 by a spring 37 compressed between a retainer cup 39 and a cover 35 fixed by bayonet action into housing 34. The cable sheath 47 is earthed to the housing 34 via grounding wires 48 which are clamped to lugs 92 on cover 35. A cast insert 40 of hard dielectric material such as epoxy resin (as shown, in two parts 40a, 40b) comprises a frusto-conical end which projects from the open end of housing 34 to present a tapering surface 41. A double ended socket contact 50 is disposed in an axial bore 80 in insert 40 having a conductive inner surface 81 to eliminate corona. Each end of contact 50, which is of square section, comprises a pinreceiving socket of circular section (Figs. 3-5, not shown) the sides of the socket being slotted (at 60) to provide a resilience which is adjustably limited by a ring 63 of Be-Cu which seats on flattened corner edges (59a) of the socket. The inner socket 50a receives a conductive pin 52 which is crimped on to the cable core 45a. The other socket 506 contains a spring-loaded core 73 of arc-extinguishing material which cooperates with a liner 72 of similar material at the entrance 42 to bore 80. As shown, socket 50b is engaged by the conductive pin 77 of a grounding cover 32, comprising a metal housing 88 containing a soft dielectric filler 90 which is compressed against surface 41 when the cover 32 is affixed to housing 34 by spring-loaded latches 66 which engage a skirt 65 on housing 34. An additional earthing wire may be connected to terminal lug 88b on cover 32. Alternatively, the cover 32 may be replaced by a surge-diverter (Fig. 12, not shown) comprising a series of quench gaps (142) and SiC blocks (143) in a conductive housing (141) also containing soft dielectric material (147) which is spring-biased into sealing engagement with surface 41 when the surge-diverter is latched on to the housing 34. To interconnect cables, a multi-socket connector (Fig. 11, not shown) may be employed. This comprises a plurality of sockets similar to sockets 50b, each within a bore in one of a plurality of limbs of a hard dielectric member, the free end of each limb presenting a surface 41 for sealing contact with a counterpart. The sockets are interconnected by a conductor within the member of hard dielectric, which is encased in a conductive housing. Connection between a cable termination and a socket of the multisocket connector is effected by a link comprising two interconnected plug pins, each associated with a conical concavity in a soft dielectric. As shown, Fig. 15, the link comprises a removable fuse cartridge 166 containing a silver fuse wire 157 wound spirally on a flanged core 159 surrounded by sand or other refractory grains 158. Plug pins 169 are removably screwed into end blocks 170. The soft dielectric 171 is compressed within conductive housing 167 by springs 172 acting between retainer cups 173 and bayonetted-in covers 168. Alternatively, a fuse unit (Fig. 14, not shown) having non- replaceable fuse wire, or a mere conductive link (Fig. 8, not shown) may be used; in each case the fuse or link is encased in hard dielectric material, soft dielectric inserts being provided to present sealing surfaces to surfaces 41 of the counterparts. One plug of a main fuse unit may be connected to a socket within a shielded conical extension of hard dielectric forming part of the unit (Fig. 17, not shown), and may cooperate with a tap fuse unit having limbs of unequal length, each comprising a plug associated with a soft dielectric sealant for respective engagement with the socket of the main fuse unit and a termination on a tap cable. In a modification (Figs. 25, 26, not shown) two loop cables are plugged into a termination comprising two interconnected sockets such as 50a and a single socket such as 50b in a conical hard dielectric riser, connection being made between the latter and a terminated tap cable by a link unit. To connect a tap cable to a component, e.g. a transformer or circuit breaker, a connector 200, Fig. 21, is provided having an L- shaped conductive housing 204 enclosing spring- compressed soft dielectric 204a in which is embedded a socket 50a for receiving plug 52 on the core of cable 45 and, at right-angles to and connected with the socket, a pin 77 for engagement in the socket 50b of a terminal 201 of component 202. To axially splice two cables, a connector (210, Fig. 22, not shown) comprises a double-ended socket contact embedded in spring-compressed soft dielectric within a conductive housing.