Abstract
We have designed and constructed a superconducting four-winding power transformer in which main windings were wound by NbTi wires developed for AC use. The maximum capacity of 72kVA was attained with high performance of efficiency and voltage regulation. The lifting weight of the transformer was about one seventh compared with conventional ones with the same scale of capacity. We also investigated the processes of quench and recovery in main windings in an accidental short test. In this test, instantaneous partial quenches occured in the main windings, and transport current was shifted from the main coils to the auxiliary ones. It was also confirmed that the short-circuit current was limited by loose coupling between the auxiliary windings. After release of short, the system was stably recovered by temporal break of the main windings, because the temperature of the main windings after quench was suppressed by an abrupt decrease of the transport current.
