Superconducting fault current limiters

Three different superconducting fault limiter designs are described in relation to low temperature (metallic) superconductors operating at 4.2 K and high temperature (ceramic) superconductor at 77 K. The three devices described are: a resistive superconducting fault current limiter (SCFCL); a saturated inductive SCFCL; and a shielded inductive SCFCL. Resistive type SCFCLs operating at 4.2 K are being considered for application by some utilities, despite being harnessed with the technology and operating costs associated with using liquid helium; the relatively low weight and volume makes it attractive in some applications. The shielded inductive type incorporating high T_c superconductor discs may be considered the most practical. Using near term state-of-the-art technology and operating at 77 K with bulk liquid nitrogen would make the device virtually maintenance free and life time expectancy should be in excess of 30-40 years