Hysteresis Characteristics of Flux-lock Type SFCL with Series Connection of Two Coils

Since the saturation of the iron core comprising the flux-lock type superconducting fault current limiter (SFCL) with series connection of two coils can prevent its effective fault current limiting operation immediately after a fault accident, the flux-lock type SFCL's design considering the hysteresis characteristics is essential. For the analysis on the hysteresis characteristics of the SFCL during the fault period, its equivalent circuit for the transformer with the nonlinear exciting branch was drawn. Through the analysis on the SFCL's hysteresis curves, which were obtained from the SFCL's fault current limiting experiments based on its equivalent circuit, the winding direction of two coils, one of the design conditions, to suppress the saturation of the iron core comprising the flux-lock type SFCL with series connection of two coils was discussed.