Development of a 66 kV-5 kArms class HTS power cable using REBCO tapes with high critical current

High temperature superconducting (HTS) cables are able to achieve large power capacity and low-loss power transmission. Fujikura Ltd. worked on developing a 66 kV-5 kArms HTS power cable using high critical current (I_c) REBCO tapes in the Japanese national project. One of the technical targets in this project was to reduce AC loss to less than 2 W/m at 5 kArms. REBCO tapes with 240 A/4 mm-width of I_c at 77 K, self field, which were fabricated by ion-beam-assisted-deposition (IBAD) and pulsed laser deposition (PLD) methods, were applied to the HTS power cable. As a result, we succeeded in developing the 20 m-long 66 kV-5 kArms HTS power cable. The measured AC loss was achieved 1.4 W/m at 77 K and 1.0 W/m at 67 K at 5 kArms. On the other hand, it is considered that the eddy current loss of the stainless-steel cryostat pipe of HTS cable become obvious in the case of the single-core cable with the large current capacity. It is suggested that the eddy current loss of the stainless-steel cryostat pipe is due to the internal magnetic flux. Therefore, the eddy current loss of the stainless-steel cryostat pipe as well as uniform current distribution of HTS conductor and shield layer should be taken into account for designing the winding direction and pitch of HTS conductor and shield layer of HTS cable. In this work, the measured eddy current loss of the stainless-steel cryostat pipe is also compared with the calculated one.