Development of superconducting triaxial cable

We have been developing triaxial superconducting cable supprted by New Energy and Industrial Technology Development Organization (NEDO) since 2015. The target thereof is replacement for Isolated Power Bus (IPB) which has capacity of 22kV-10kA. We manufactured prototype 15m-long 3kA cable and one set of terminations. The cable used in house YBa
₂
Cu
₃
O
_7-d
(YBCO) tapes made by MOD (Metal-organic deposition) process. In ordwe to checki electrical insulation strengeth, AC and lightning impluse break down tests were performed with 600mm-long model cables in liquid nitrogen at atmospheric pressur. We designed cable, and withstand voltage test and partial dischage test were perfomed. The specifications thereof were AC voltage of 52kV for 30minutes and lightning impulse of positive and negative 125kV each in 10times, and partial discharge of 36kV. Thereafter, we designed triaxial terminations. Heat insulation thereof needs both heat and electical insulation characters. To check both insulation characteristics, we produced one-phase model termination. As a result, application of vacuumed insulation for high voltage parts was difficult, so that atmospheric pressure and solid insulation were applied for heat insulation part. In this condition, the system met the withstand voltage test. We assembled a triaxial superconducting cable and termination and cooling system, and system tested based on CIGRE TB 538.