Investigation on reduction of required superconductor volume in a resistive fault current limiter with Bi2223 bulk superconductor

The bulk high temperature superconductor of low J_c is difficult to be heated up over T_c quickly within a period of the initial 1/4 cycle during a fault. Therefore, a large volume of superconductor will be required to obtain the required current limiting impedance, because a short-circuited current has to be limited by the flux flow resistance. Even in case of J_c of 2000 A/cm², the volume will amount to around 0.1 m³ in order to limit a fault current to less than 3 times the J_c value for 6.6 kV-1000 A fault current limiter. In this paper, a method in which a perpendicular magnetic field is applied automatically to the bulk superconductor during a fault is proposed. And it is revealed that the volume of superconductor will be reduced by three times less than the one required in the conventional method.