Influence of the Relative Position of Conductors Constituting Each Phase on the AC Loss in a Three-Phase Coaxial HTS Cable

Three-phase coaxial high-temperature superconducting (HTS) cables have three layers, and HTS conductors are arranged circularly in each layer. Since each arranged conductor transports current, the conductor arrangement determines the magnetic field distribution inside the cable. In addition, the AC loss varies depending on the conductor arrangement because the magnitude of the perpendicular magnetic field on each conductor determines the AC loss of the cable. Therefore, it is essential to consider the optimal conductor arrangement in cable design. In this study, we investigated the influence of the relative position of the conductors constituting each phase on the AC losses. The conductors constituting the cable were Y-based superconducting conductors, and the AC losses were calculated by one-dimension finite element analysis of the T-method. The calculation results show that shortening the gap between conductors in the radial direction reduces the AC loss. Furthermore, we have shown that simultaneously shortening the circumferential and radial gap between conductors can significantly reduce AC losses. In addition, the cost estimation shows that it is essential to consider a conductor arrangement with low AC losses in cable design.