Design of Helically-Wound Superconducting AC Power Transmission Cables

Conceptually, one phase of a proposed three-phase power transmission system consists of a pair of coaxial tubes or pipes, with superconductor on the outside of the inner pipe and on the inside of the outer pipe. Although rigid versions of this concept have been under development for nearly a decade there are strong economic and technical reasons to develop a flexible form of cable. In this construction the conductor and insulation are wound as concentric helices, thus permitting many of the advantages of flexibility to be reaped at the expense of several new problems not encountered in plain concentric cylindrical designs. In this paper the electrical complications arising from helical current paths are discussed. The practical manifestations are primarily heating of the normal metal used in the cable and undesirable voltages appearing on the outer conductor.