Recovery Behaviors of the Transformer-Type SFCL With or Without Neutral Lines

This study was to analyze the recovery characteristics for the superconducting element in the transformer-type superconducting fault current limiter (SFCL) consisted of iron core, elements in primary and secondary windings. The superconducting element was connected to the secondary windings of a transformer-type SFCL in series. In order to increase the power capacity of the SFCL, the number of the superconducting elements should be increased and the recovery time of each superconducting element should be also shortened. When the number of superconducting elements in secondary winding was increased, the recovery time of the superconducting elements according to the voltage increase in the transformer-type SFCL grew longer because of unbalanced quenching of the superconducting elements. However, as for the transformer-type SFCL that has neutral lines connected between the secondary winding and the superconducting elements, the recovery time grew shorter due to the enhancement of quenching behavior. The transformer-type SFCL with the neutral lines was more profitable for the capacity increase of the SFCL.