Current Limiting and Recovery Characteristics of SFCLs Using Magnetic Coupling of Two Coils

Superconducting fault current limiters (SFCLs) using magnetic coupling of two coils can be divided into the insulated type SFCL and the non-insulated type SFCL depending on whether the two coils are insulated through one iron core or not. Among such SFCLs, the transformer type SFCL belongs to the insulated type SFCL because of its insulated two coils. On the other hand, the flux-lock type SFCL, its two coils electrically connected in parallel or series, can be classified into the non-insulated type SFCL. Basically, the structural component and the operational principle of these SFCLs rely upon the magnetic coupling of two coils, and might therefore be considered to be the same. However, there are important differences in the current limiting and the recovery characteristics of these SFCLs depending on design conditions such as the winding direction and the inductance ratio between two coils. In this paper, the current limiting and the recovery characteristics of SFCLs using magnetic coupling of two coils were investigated through the fault-current limiting and the recovery experiments. Through the analyses of the experimental results, the current limiting and the recovery characteristics of the SFCLs were confirmed to be affected by the SFCL's operational current.