Analysis, design and experimental results for a passive current limiting device

The authors report on the development of a passive magnetic fault current limiter (FCL) with the following attributes: compactness, small size, reliable and fail-safe operation, and zero reset time. The limiter consists of two magnetic devices connected in series and in magnetic counter opposition to each other. Two designs are considered. In one design, Nd-Fe-B permanent magnets are sandwiched between the pole faces of two saturable ferrite E-cores. In the other design, Nd-Fe-B permanent magnets are sandwiched between the pole faces of two steel E-cores with built in zones of constriction. A design procedure is developed and a design example for the ferrite and steel based core is illustrated. The transient performance of both FCL designs is simulated by means of the tableau approach. Experimental results for both designs are presented to verify the validity of the proposed tableau approach, the design procedure and the functional operation.