Reliability Implications in the Design of Fault Current Limiters

This paper is principally concerned with the implications of FCL reliability upon the design and application of fault current limiters. The paper examines the following important questions: I) Can devices which are designed to meet present functional specificationis for fault current limiters be made compatible witlh the implicit need for reliability and economy? 2) Sinice no device will ever be fully reliable, what are the consequenices of FCL failure, anld what constitutes reasonable backup protectioni? 3) Cain the nieeds whlichi have spawned the quest for the FCL be met better in a manner more consistent with the essential needs for economy and reliability by modifying the functional specifications? t 4) For puirposes of backup protection, would a limiter which responds only after the first current loop has been allowed to pass be of any worth? 5) Are there any significant improvements or benefits in the tolerance of apparatus to momentary currents if severe fault currents are limited to a single current loop?