Patent ID: 7943852

Claim:
A superconducting cable formed by twisting together a plurality of cable cores, each having: (a) a superconducting conductor layer; (b) an insulating layer provided on the outer circumference of the superconducting conductor layer; and (c) an outer superconducting layer provided on the outer circumference of the insulating layer; the number of cable cores being two, wherein the insulating layer is: (a) formed by a combination of insulating paper and composite paper composed of insulating paper and plastic film; and (b) structured by using a ρ grading such that as the radial position moves toward the innermost portion of the insulating layer, the resistivity decreases, and as the radial position moves toward the outermost portion, the resistivity increases in order to flatten the radial distribution of a DC electric field in the insulating layer.