Design and evaluation of 66 kV-class HTS power cable using REBCO wires

Abstract

Sumitomo Electric (SEI) has been involved in the development of 66kV-class HTS cables using REBCO wires. One of the technical targets in this project is to reduce the AC loss to less than 2W/m/phase at 5kA. SEI has developed a clad-type of textured metal substrate with lower magnetization loss compared with a conventional NiW substrate. In addition, 30mm-wide REBCO tapes were slit into 4mm-wide strips, and these strips were wound spirally on a former with small gaps. The AC loss of a manufactured 4-layer cable conductor was 1.5W/m at 5kA at 64K. Given that the AC loss in a shield layer is supposed to be one-fourth of a whole cable core loss, our cables are expected to achieve the AC loss target of less than 2W/m/phase at 5kA. Another important target is to manage a fault current. A cable core was designed and fabricated based on the simulation findings, and over-current tests (max. 31.5kA, 2s) were conducted to check its performance. The critical current value of the cable cores were measured before and after the over-current tests and verified its soundness. A 5kA-class current lead for the cable terminations was also developed. The current loading tests were conducted for the developed current leads. The temperature distribution of the current leads reached to the steady-state within less than 12h, and it was confirmed that the developed current lead has enough capacity of 5kA loading.