Development of a superconducting fault current limiter using various high-speed circuit breakers

The authors constructed and tested a model superconducting fault current limiter (SFCL) using a high-temperature superconducting film according to a design that includes a vacuum interrupter with an electromagnetic repulsion mechanism. The superconductor and the vacuum interrupter are connected in parallel with a bypass coil. If a fault occurs and current flows through the system, the superconductor is quenched and the current is transferred to the parallel coil because of the voltage drop in the superconductor. This large current in the parallel coil actuates the magnetic repulsion mechanism of the vacuum interrupter. On opening the vacuum interrupter, the current in the superconductor is interrupted. This model is expected to exhibit very low-energy consumption by the superconductor. The authors succeeded in interrupting the current flowing in the superconductor within a half-cycle using a prototype SFCL. An improved SFCL with higher voltage and current ranges was used to carry out current-limiting tests and to investigate the possibility of adapting our SFCL in a power system. The authors also carried out a currentlimiting test using a conventional high-speed vacuum circuit breaker (HSVCB) as a new method for realising our concept.