Fundamental characteristics of a 200A-class HTS reactor

In order to develop a reactor for a LC resonance-type fault current limiter, we have been studying a pancake-type HTS coil with a low loss and a high current capacity. Double-pancake coils wound by Bi2223 tape wire are adopted as a unit coil for the reactor. In the double-pancake coil, two Bi2223 tapes are wound in parallel to each other to obtain a high current capacity. Besides, a stainless steel wire is co-wound with the Bi2223 tapes in order to increase the mechanical strength. The reactor is designed as an air-core type one to obtain a constant inductance. 12 unit double-pancake coils are manufactured. They are located in a toroidal shape in order to obtain symmetry. 12 unit coils are connected in "3-parallel/4-series" mode. The critical current, the AC loss, and the current sharing ratio between the unit coils are measured. From the experimental results, it has been confirmed that the current sharing among the 3 parallel circuits is uniform, in spite of some deviations between the critical currents of each unit coil.