Abstract: We consider a dc superconducting cable design consisting of four concentric metallic cylinders, of which two carry the load current and two comprise the cryogenic enclosure. When a transient voltage is impressed across such a cable, the major dielectric may not be fully stressed to its design value, and unwanted voltage stresses may develop across other parts of the cable. This paper analyzes the surge-voltage propagation characteristics of a four-conductor dc superconducting cable for a step-function input voltage. This analysis, although mainly directed to superconducting cables, is also applicable to other-multiconductor tranmission lines. A companion paper discusses the parametric effects of the cable system in optimizing the voltage distribution.

Abstract: This paper gives some observations on the insulation properties and on the type test method of ±500kV self-contained oil-filled(OF) dc cable including some accessories. The cable and accessories were subjected to a withstand test at the factory laboratory, to a type test recommended by CIGRE SC-21 for dc cable (abbreviated as CIGRE Type Test) for a short sample and to a long-run test on a long cable sample at Takeyama Cable Testing Station. At the first step some cables experienced breakdown, however, at the final stage all cables successfully withstood the above tests and also the more severe supplementary tests.