三相同一軸高温超電導ケーブルの交流損失における撚りピッチ依存性に関する研究

抄録

High-temperature superconductor (HTS) cables have been intensively studied because they are more compact compared with conventional copper cables. Since it is strongly expected that HTS cables will replace conventional power lines, some HTS cables have been designed, manufactured, installed in power grids and tested to demonstrate full-time operation. Recently, a triaxial cable composed of three concentric phases was developed because of the use of fewer HTS tapes, small leakage field and low heat loss when compared to three-coaxial HTS cables. The layers inside the triaxial cable are subject to azimuthal fields applied from inner layers and axial fields applied from outer layers with different phase from their transport currents. These out-of-phase magnetic fields should be calculated under the condition of the three-phase balanced distribution of the triaxial cable, and thereby AC losses should be evaluated. In this paper, the AC loss in the triaxial HTS cable consisting of one layer per phase is theoretically treated for simplicity. The AC losses in the cable are calculated as functions of the twist pitches of HTS tapes. It is found that the AC losses rapidly decrease with increasing twist pitch.