SUPERCONDUCTING FAULT CURRENT LIMITERS

50-60 Hz electrical engineering represents a considerable potential ma rket for superconductors. Fault current limitation will probably be th e first among the possible applications, to find an industrial opening . Exploited features are very specific of the superconductors, namely the large contrast existing between an on-state with high current dens ity and an off-state with high electrical resistivity, obtained as soo n as the current reaches a specified level. It thus becomes possible t o warrant the grid from any current excursion over a specified value, with considerable impact on the protection and dimensions of conductor s and devices, and increased possibilities of interconnexion. The curr ent limiter technology is rather complex ; different structures have b een proposed and tested ; they are resistive or inductive, based on lo w-T(c) or high-T(c) superconductors. The most advanced candidate to da te is a resistive structure, using conductors made of ultra-fine niobi um-titanium filaments in a coppernickel matrix, whose essential featur es are described hereunder.