Abstract
With the recent abvent of high-performance AC superconductor with very small AC loss and large current carrying capacity, the possibility of air-core superconducting transformer is being studied. Though the exciting current is very large, the air-core transformer has merits of (1) no iron loss, (2) no insulation care to the core, (3) no harmonics, and no inrush current induced by iron saturation, etc.. So, the authors fabricated and tested a small experimental transformer (2.5kVA, 330/150V). As easily predicted, the exciting current becomes very large. It occupies about 45% of the rated current. Meanwhile, the leakage reactance increases considerably. The %IX becomes about 28%. These experimental results show good agreement with the theoretical analysis based on a equivalent circuit.
