DEVELOPMENT OF POLYMER-INSULATED SUPERCONDUCTING POWER-CABLES

A solid electrical insulation design was proposed for the very simple version of a superconducting cable by incorporating polymeric materials suited for the cable extrusion. The features of this insulation lie in the exclusion of electrically vulnerable cryogens from the electrical insulation and in the exploitation of excellent insulation capability of polymers in the cryogenic temperature region, which may realize the reliable operation for the long run. Since cryogen circulates in the central core pipe, it can either be cold helium or nitrogen corresponding to the working temperature of adopted superconductors. Low-density polyethylene, cross-linked polyethylene and ethylene propylene rubber were successively applied to the extruded electrical insulation of the cable. The cooling characteristics and voltage tests were repeated. It turned out that ethylene propylene rubber behaved satisfactorily even at liquid-helium temperature.