GB1421044A - Ultralow temperature cable magnetomotive bistable switching device - Google Patents

Abstract

1421044 Low temperature cable FUJIKURA CABLE WORKS Ltd 4 Oct 1973 [7 Oct 1972] 46388/73 Heading H1A A cable for use at low temperature comprising conductors helically wound on a round insulation core is constructed so that shrinkage in core diameter on reduction in temperature is related to the shrinkage in conductor length so that the pitch of the helix, and hence cable length, remains constant. The cable parameters are chosen to satisfy the equation where P is the pitch, x = (L-L<SP>1</SP>)/L, D and D<SP>1</SP> are the core diameters at atmospheric and low temperatures respectively and L is the length of one pitch of conductor at atmospheric temperature and L<SP>1</SP> is the corresponding length at low temperature. In an embodiment described, Fig. 6, a polytetrafluoroethylene core, which may have one or more bores for the passage of coolant, or may be solid, is helically wound with Al conductors 2. These are covered by a layer of rolled semiconductor tape 3, a layer of polyethyleneimpregnated paper 4, a layer of metal tape 5 and a plastics layer 6. At atmospheric temperature the conductors do not contact one another (Fig. 7, not shown). The low temperature mentioned is that of liquid nitrogen.