Thermo-mechanical properties of a 66 kV superconducting power cable system

To verify the practicability for intended application, TEPCO and SEI have jointly developed a 100 m, 66 kV class High Temperature superconducting power cable system and tested for a long duration one year at the CRIEPI test site. The cable has three cores in a cryostat and a cold dielectric configuration. The three cores are stranded loosely to manage thermal contraction during the cooling process. The cable is warmed to room temperature after each test to investigate the influence of the cooling cycle. At the initial cooling of the system, the tension of the cable due to thermal contraction during the cooling process was measured to be about 8 kN, which is considerably lower than 50 kN measured in a short length model cable without measures against thermal contraction. System properties, such as critical current, AC loss, shield current and so on are measured during each test after the cooling cycle. During the test program, the system shows no change in its properties.