Resistive Superconducting Fault Current Limiters Are Becoming a Mature Technology

Resistive superconducting fault current limiters (rSFCL) are reliably reacting devices and excellent means to overcome issues of higher short circuit current levels resulting from added electricity generation and more interconnected networks. Due to the strong impedance increase of the superconductor components initiated by a fault and the very low reactance under all operating conditions the rSFCL technology is ideal for protection of electricity grids. Several rSFCL systems based on different superconductor materials have been designed, built, tested, and commissioned by Nexans SuperConductors at distribution grids of several DNOs and also two times at a power plant. A recently built system is operating together with a HTS cable to supply up to 40 MVA on 10 kV enabling a very compact cable design. First market opportunities for medium voltage SFCLs have been identified and fully commercial projects targeting at permanent installations are now becoming reality. Different development stages leading from first trial devices to real commercial systems are presented including further necessary steps for SFCLs getting close to serial production.