A proposal of new operating procedure of transformer type fault current limiter

Recovery time of a superconducting fault current limiters (SCFCLs) of a transformer type is very short, because the fault current is limited by the inductance of the primary coil and the amount of energy dissipation in the secondary superconducting wire is small. The temperature of the secondary winding of the SCFCLs decreases even in the current limiting operation. It was pointed out that the SCFCL in the current limiting mode may recover to the waiting mode by shunting the current for a certain time. Recovery characteristics by FCL-short-circuit was studied experimentally. New operating procedure based on the recovery by FCL-short-circuit is proposed. Required FCL-short time for successful recovery was measured for various conditions. The availability of the proposed operating procedure was investigated using a one-machine infinite bus system with parallel, transmission line including 3-phase SCFCL unit.