After extensive research of superconducting fault current limiters for electric power systems, we report that we were successful in developing a new one. We developed a superconducting fault current limiter. It has a superconducting cylinder as the active element, and we chose Bi-2212 thick film for the cylinder as a superconductor. However, Bi-2212 thick film has low critical current density (Jc). It is necessary for the practical use of the superconducting fault current limiter that the superconductor has high Jc. So to get high Jc, we tried Bi-2223 as superconductor material, and prepared Bi-2223 thick film. The raw paste of the Bi system was sprayed on an MgO substrate, then sintered in the air with intermediate pressing by a cold isostatic press method (CIP). The sintered Bi-2223 thick film had good orientation of the polycrystalline. The Jc of the 270μm thick film was 7, 000A/cm2 (Ic=94.5A) at 77K. The Jc changes depended on the thickness of the film, and dropped drastically when the thickness of the film become thinner than 150μm. As a result of our investigation by XRD, ICP and EPMA make it clear that a decrease of Pb affects Jc.
