Study of an Air-Core High Temperature Superconducting Current Transformer for Large Current Supply

Large AC current supply is essential for measuring the current transport characteristics of superconducting wires, such as AC loss in helical coil conductors. Commercial current supplies are generally too large and heavy, and therefore, they are inconvenient to use with the superconducting wires. The authors have been studying a small and lightweight large current supply with a high temperature superconducting (HTS) current transformer. An air-core HTS current transformer is suitable for the miniaturization of AC supply because this transformer does not have an iron core and thus does not have large volume and heavy weight. In this paper, we report that the current supply with the air-core HTS current transformer can output large current with high frequency by using the resonance phenomenon. Furthermore, we provide a method for the detection of normal transitions in the transformer by measuring the current transformation ratio of its primary and secondary currents. This detection method is composed of a simple measurement system, and experimental results show the usefulness of this detection method for the air-core transformer. (C) 2021 The Japan Society of Plasma Science and Nuclear Fusion Research