US Patent 7598458 Super-conductive cable

A superconducting cable according to the present invention includes a former, a superconducting conductor layer formed around the outer circumference of the former, an electric insulating layer formed around the outer circumference of the conductor layer, a shield layer formed around the outer circumferential of the insulating layer, and a normal-conducting metal layer formed between the insulating layer and the shield layer. The normal-conducting metal layer existing inside shield layer has an inductance greater than that of the shield layer, which can suppress a rise in temperature in the event of accidents such as short-circuits, and also can reduce AC losses since currents flow through shield layer during the passage of normal currents.