Impedance Characteristics of Non-Inductive Coil Wound With Two Kinds of HTS Wire in Parallel

In order to minimize the impedance in nominal current, non-inductive superconducting coil can be applied to SFCL. In a few former researches on the coil, the two wires connected in parallel were same. This conventional coil generates only resistive impedance during a fault. This paper proposes non-inductive coil wound with two kinds of HTS wire in parallel. Since properties of the two wires such as index number and resistance of stabilizer are considerably different from each other, current distribution between the two wires is unequal. The unequal current distribution induces difference of magnetic flux between the two windings. Hence, the proposed coil generates inductive impedance as well as resistive one. To fabricate proposed coils, three wires were used; Bi2223 tape, copper-stabilized Y123 coated conductor (CC) and stainless steel (SS)-stabilized CC. The short-circuit test of the coils were conducted to investigate the impedance characteristics. As a result, the proposed coil wound with two kinds of wire has inductive impedance. Even if the inductance was small because of short wire length, it is obvious that our proposed coil make magnetic field. The magnetic field can be applied to commutate a fast switch in hybrid SFCL systems.