Current-Lead Design for Cryocooled HTS Fault Current Limiters

A comprehensive design procedure is presented for the current leads in HTS fault current limiters continuously refrigerated by a cryocooler. Two specific aspects are focused here in addition to the standard lead-design. The first is an optimization with taking into account the heat conduction through electrical insulator needed for high-voltage applications. Through a rigorous analysis, it is verified that the standard design should be modified in order to minimize the overall heat leak. The second is the transient thermal behavior that may be caused by excessive current. A numerical analysis is performed to estimate the peak temperature after a short current-limiting period, including the effect of fins as enhanced local heat capacity. Some of the design details are demonstrated for the specifications of FCL´s under development in Korean R&D programs.