GB1340983A - Superconductor cables - Google Patents

Abstract

1340983 Super-conducting cables SIEMENS AG 3 March 1972 [10 March 1971] 10174/72 Headings H1A and A4D An electrical conductor comprises a strip of super-conducting material wound into a helix along the inside of a tubular support structure and another strip wound helically on the outside of the structure so that the strips are flexible with the structure at room temperature. The tube may be made up of layers 31, 32 of polyethylene, polyterephthalate or a polyamide in mesh foam and a multilay or winding 33 of, e.g. polyethylene fibre or polytetrafluoroethylene fibre paper. Layers 31, 32 may be made impermeable by briefly heating to about 150‹C. Strips 6, 9 comprise a layer of niobium or lead 38, 39 facing the support, and are backed with a normally conductive metal, e.g. copper 36, 37. Preferably the two layers in each strip are offset, see Fig. 8 (not shown), so that the super-conductive layers, but not the normally conductive layers, overlap even after cooling. A modified support structure, see Fig. 4 (not shown), comprises solid plastics tubes (41) connected end to end by a tongue and groove arrangement which obviates tensile stresses during cooling. A method of connecting two sections together, Fig. 5, comprises inserting a niobium-coated copper tube 55 into the ends of the inner tubes 56, 57 removing the copper from ends 60, 61 of the inner helixes and welding the ends to tube 55, inserting packing pieces 64, 66, 67 of plastics, 73, 74 of ceramics or asbestos and welding the ends 68, 69 of the outer helices to each other as in Fig. 7 (not shown). Alternatively, the pieces 73, 74 may be of niobium and the ends 68, 69 welded to these. Three conductors may be made up into a cable Fig. 1 (not shown) surrounded by rigid or flexible coolant and protective tubes.