Patent GB-450375-A (GB)
Title: Improvements in trunk communication electric cables with air space insulation
IPC: H01B11/18
Filed: 1935-09-27
Abstract: 450,375. Electric cables. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. Sept. 27, 1935, Nos. 26822, 26823, 26824, 26825, and 26826. Convention dates, Sept. 27, 1934, Nov. 3, 1934, Nov. 20, 1934, Aug. 13, 1935, and Aug. 29, 1935. [Class 36] In a high - frequency cable with air-space insulation the conductors are located in or at kinks in individual turns of a relatively rigid insulating string element wound in open turns about an axis extending longitudinally of the cable. In the case of a stranded double or quad line the kinks are of such a depth that the distance of a conductor from the usual surrounding metal sleeve is approximately half the distance between the diametrically disposed conductors. The string is preferably round in section but may be of other shaped, e.g. square, or it may be formed as a band. It may have a reinforcing core, is preferably formed of polystyrol and is wound and indented simultaneously with the stranding thereon of the conductors. Fig. 1 shows a twisted double line comprising tubular conductors 10, 11 located in diametrically opposite indentations in the windings of the insulating string 12 of round cross-section. An insulated string binding 15 holds the conductors in position, and an insulating sleeve 16 formed. from a band winding, a screen 17, another insulating sleeve 18 and the outer water-tight jacket 19, are successively applied. The string 12 may alternatively be wound in the form of a figure 8 and the conductors located in the indentations formed thereby. For a spiral quad line the conductors 20, 21, 22, 23, Fig. 3, are located in the indentations shown in the helical open wound string 24 and secured by a string 25. The cable may be used in side and phantom circuit operation. Fig. 4 shows a concentric cable comprising an inner tubular conductor 32 secured for example by adhesives or clamping within the indentations 31 in the helically wound string 30, surrounded by an insulating sleeve 33, the outer conductor 34, an insulating sleeve 35 and lead jacket 36. The conductors 40, 41, Fig. 5, in a twisted double line are of strip form and secured on the flattened portions of the string winding 42 by a string winding 43 and located centrally of the cable by an open helical insulating winding 44 surrounded by insulation 45, screen 46, insulation 47 and outer jacket 48. In a modification the string spacing winding may be subdivided. Figs. 6, 7 show two string windings 51, 52 separated by insulating strings 58, 59 the inner tubular conductor 50 being located in indentations 53 in the strings, and secured therein by a supplementary string (not shown). The outer conductor 55 applied over the insulating sleeve 54 is formed of spirally wound thin bands 55<1> between which wires 55<2> are inserted to prevent displacement of the bands. Over this outer conductor an open band winding is applied, an insulating sleeve 56 and lead jacket 57. In the case of a twisted double line both conductors are held in spaced indentations in the diametral portions of the string windings 51, 52. In another embodiment the conductors are not held in the indentations of the string winding but secured thereto. For example, Fig. 9, shows the inner conductor 70 of a concentric cable located between the indentations in the string winding 71 and secured thereto by insulating strings 72, 73 located in the indentations and an insulating band winding 74. The sleeves 75, 78, 79 and outer conductor 76 are formed as described with reference to Fig. 6. In another embodiment, to secure adequate air-space between the conductors and the surrounding screen subsidiary string windings may be provided. Fig. 12, for example shows conductors 90, 91 located in the indentations of the string winding 92 and surrounded by a closed or open wound insulating sleeve 93 over which open insulating string windings 94, 95 are applied followed by the insulating sleeve 96, screen 97 insulating sleeve 98 and lead jacket. In a modification of the embodiment shown in Fig. 4, the open string winding 101, Fig. 13, is wound in open turns around the conductor 100 and the sleeve 104 located between the outer conductor 103 applied over an insulated band winding 102, and outer water-tight jacket 105 may be of insulating material, conducting material for example copper or a magnetic material. The winding 101 may be formed round a shaping mandrel and the indentations formed by heating and pressing the string into a groove in the mandrel, the shaping being effected either before or during application of the string to the conductor. This embodiment of the invention is also applicable to cables with one or more double or spiral quad lines.