Development of a Compact HTS Current Transformer for Evaluating the Characteristics of HTS Conductors

In order to realize HTS power devices with high performances, it is important to evaluate the characteristics of HTS conductors theoretically and experimentally. In the experimental evaluation, an ac power supply with a large current capacity and few ripples is necessary. To this end, we developed a compact HTS current transformer for evaluating the characteristics of HTS conductors. This transformer is wound in an elliptical shape with using Bi-2223 tape. The secondary current of the current transformer can be induced at about 1 kA at 77 K when the primary current is 40 A. The transformer was fabricated very compactly, and the externals size is 70 mm in the diameter, and 110 mm in length. To confirm the practicality of the transformer, the current was actually energized to an HTS conductor composed of 16 Bi-2223 tapes. The results of the performance test of the current transformer and the method of increasing the current capacity of the current transformer are also discussed.