A proposal of fast self-acting and recovering magnetic shield type superconducting fault current limiter and the analyses of their characteristics Original Research Article

A high-performance magnetic shield type superconducting fault current limiter (MSFCL) has been proposed. It will be fast activated automatically when a short circuit failure occurs. And it will be recovered to superconducting state in a short period of time after the fault is cleared. The designed magnetic shielding body consists of a large number of the flat Bi2223 rings. They are stacked with a small gap between each ring and hence the cooling surface is increased by about 10 times that of an usual tubular shielding body. The toroidal coils (TCs) will be wound around the rings so that a magnetic field may be applied to the rings in a circumference direction. The thin heaters similar in form to the flat ring will also be stuck on both sides of each ring. It is shown that the rings will be automatically heated quickly up to Tc or more and accordingly a faster current limiting action will be realized by these two additional effects. A fairly fast recovery to a superconducting state after a fault is also clarified.