Development of RE-123 Superconducting Cable

High temperature superconducting (HTS) cables are expected as a large capacity cable with lower transmission loss. Numerous HTS cable demonstration projects using Bi-2223 superconducting wires are being promoted around the world for practical utility usage. RE-123 coated conductors, which are still at the research and development stage, will also be applied to several demonstration projects in coming years in addition to Sumitomo Electric's world first 30-m HTS cable project using RE-123 conductors which was successfully energized in early 2008. As wire and cable manufacturer, Sumitomo Electric has also been developing it's own RE-123 conductors, and has succeeded in fabricating a 200-m-class conductor. One of the important challenges associated with the use of RE-123 conductors in power cables is to ensure stability against over-current. In order to evaluate over-current characteristics, a 10-meter ldquo3-in-Onerdquo RE-123 superconducting cable was manufactured and over-current tests were performed. No Ic degradation was observed after exposure to over-currents with a maximum current of 31.5 kArms for 2 s (120 cycles), which meets the requirements for 66-77 kV class power cables in Japan. It was confirmed that RE-123 conductors have satisfactory over-current characteristics for use as superconducting cable wires.