Development of a large-capacity superconducting cable for 1000 kVA-class power transformers

A large-capacity superconducting cable for 1000-kVA-class power transformers has been designed and fabricated. The cable is a triply stacked multistrand (6*6*6) type. The elementary strand has 19050 NbTi filaments 0.63-mm thick in a CuNi matrix. The test cable is installed as the secondary winding in a superconducting transformer with iron core in a room-temperature space. The primary winding is the second-level subcable of the secondary one and the turn ratio is nearly 14. The designed capacity of the test cable is 4.545 kA at the secondary voltage of 220 V. The peak value of the current, 6.43 kA, is 78% of the critical current on the load line. The maximum current of the cable at 60-Hz operation was 3.78 kA (peak). The experimental results suggest that the degradation in maximum current of the test cable is related to current transfer between the cable and the copper terminal plate.<
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