R&D status of fault current limiters for utility applications

Power systems have to be designed to withstand mechanical and thermal stresses caused by short-circuits. Fault current limiters (FCLs) are new and attractive devices to reduce short-circuit current levels significantly without adding additional impedance during normal operation. This paper summarizes the present R&D status of new FCL technologies, in particular superconducting FCLs (SCFCLs). At present SCFCLs are not commercially available but first field tests of medium voltage demonstrators showed the technical feasibility. In general, different types of SCFCLs have been developed and it depends very much on the specific application which type fits best the requirements. For the future, the two major R&D objectives are to develop high voltage SCFCLs (>100 kV) and simple and low cost SCFCLs for medium voltage levels (6-36 kV)