Patent GB-739684-A (GB)
Title: Improvements in and relating to electrical transmission lines
IPC: H01R24/40
Filed: 1954-04-21
Abstract: 739,684. Cables; two-part couplings. DRILLING RESEARCH, Inc. April 21, 1954 [April 23, 1953], No. 11575/54. Classes 36 and 38 (1). A transmission line for use with an oil-well drill pipe comprises a number of conducting sections with an annular bridging assembly comprising coaxial annular bridging conductors between adjacent sections, each conductor of the conducting sections having a terminal portion aligned with one of the bridging conductors for wiping, resilient engagement therewith and the bridging conductors being rigidly supported by insulation. Each conducting section may comprise coaxial conductors 401a, 403a and an outer sheath 411, the parts being separated by insulation 401b, 403b (Fig. 3). Seated in the end of sheath 411 and protruding therefrom is an annular sealing member 408 formed with circumferential slots 408a. The bridging assembly comprises coaxial conducting members 405 406 and sheath 410, each end of each conducting member being longitudinally slotted to form spring fingers and the parts being separated by insulation 406a, 406b. The bridging assembly is positioned on a lower section of transmission line having a central conductor 401 and the upper section lowered until conductors 401a, 403a are engaged by the spring fingers of members 405, 406, the lower part of seal 408 seating in sheath 410, and insulation 401b, 403b sliding within insulation 406a, 406b, respectively. Each section of the line may be provided with sets of arms 412b, rigidly or rotatably mounted on sheath 411, which engage with brackets 412c secured to the inner wall of a surrounding drill-pipe section (not shown). Fluid in the surrounding pipe is prevented from penetrating between sheaths 410 and 411 into the transmission line by seals 408. In a second embodiment (Figs. 6 and 11) the conductors 421, 422 of the transmission line are semi-annular. These are connected to. ter; minal conductors 423, 424, which may be annular or semi-annular, are of different lengths and disposed at different radial distaces from the centre of the line. An inner annular sheath 434 (Fig. 6) is spaced from the conductors 421, 422 by insulation (not shown) and is provided with an annular sealing member 435 at each end. Insulation (not shown) is also provided between the other conducting members. The bridging assembly comprises an inner sheath 436, slotted coaxial conductors 425, 426 and insulating layers 426a, 426b and 425b, and makes sliding contact with the transmission line terminals 423, 424. Where the terminals are semi-annular, conductors 421, 422 may be alternately connected to longer and shorter terminals 423, 424 to transpose the conductors (Fig. 14, not show). The tube formed by the inner sheaths (Fig. 6) provides a fluid passage, the fluid being'provented from penetrating the transmission line by seals 435. The line may be assembled with sections of a drill-pipe 431 which are connected together by a threaded coupling member 430, the lower end of which is permanently connected to the upper end of the lower section of the pipe. Insulation (not shown) is provided between the line and the pipe.