Reducing transmission loss of the high temperature superconducting power cable

High temperature superconducting (HTS) cables are expected to be adapted to large power transmission compact type cables. HTS cables have not only high current density and low AC loss but also some environmental merits such as energy saving, CO₂ gas reduction and magnetic shielding. In general, HTS tapes of the HTS conductor and shield layer of the HTS cables are wound in spiral form, and become a multi-layer winding with large current. As a result, since the HTS conductor and shield layer are a multiple coil structure with different winding pitches, the internal magnetic flux exists in the longitudinal direction. Therefore, in the AC cable, the eddy current loss is generated in the former. In addition, since the eddy current is induced in circumferential direction in the cryostat pipe in the case of the single-core cable, the joule loss is generated. It is considered that the magnitude of the magnetic flux (loss) depends on the winding direction, winding pitch of the HTS tape and the magnitude of the current, and comes actualized together with the large current. Therefore, in order to reduce the loss of the entire cable, each loss reduction for the former, the HTS conductor, the HTS shield and the cryostat pipe is necessary. In this paper, we report on these low-loss measures of Fujikura Ltd. (author)