Development of 66 kV class REBCO superconducting cable

Sumitomo Electric Industries (SEI) has been involved in the development of 66 kV/5 kA-class HTS cables using REBCO wires. One of the technical targets was to reduce the AC loss to less than 2 W/m/phase at 5 kA. SEI developed a clad-type textured metal substrate with lower magnetization loss than NiW substrates. REBCO wires of 30 mm wide were slit into 4 mm-wide strips, and these strips were wound spirally on a former with small gaps. The measured AC loss of the manufactured cable was 1.8 W/m/phase at 5 kA, achieving the AC loss goal. Another important target was to manage fault current. The copper protection layers were designed based on simulation findings. Fault current tests (max. 31.5 kA, 2 sec) showed that the designed HTS cable has the required withstanding performance. The development of the elemental technologies was finished on schedule, and a 15 m-long HTS cable system will be constructed to demonstrate that it meets all the required specifications.