Fault Current Limiting Characteristics of Transformer-Type Superconducting Fault Current Limiter Due to Winding Direction of Additional Circuit

In this paper, the transformer-type superconducting fault current limiter (SFCL) with additional circuit, which could limit the fault current through twice quench operations, was suggested. The suggested SFCL includes one primary winding, two nonisolated secondary windings wound on the same iron core, and two high-TC superconducting elements connected with each secondary winding. The advantage of the suggested SFCL is that it can perform the twice current limiting operations due to the transient amplitude of the fault current. Among its design parameters, the winding direction of another secondary winding comprising the additional circuit of the transformer-type SFCL or the nonisolated secondary winding is expected to affect its fault current limiting characteristics. To analyze the dependence of the fault current limiting operation on the winding direction of two nonisolated secondary windings, two limiting operational currents from its electrical equivalent circuit were derived. Through the fault current limiting tests for the suggested SFCL, the fault current limiting characteristics of the SFCL were discussed.