[Show abstract][Hide abstract] ABSTRACT: This paper describes the breaking ability of a small model of a fault current limiting circuit breaker (FCLCB), which consists of an air relay unit and a flux flow resistive type of a superconducting FCL unit with a high Tc B2223 bulk. Two Bi2223 elements were connected in series as an elementary FCL unit. Current carrying tests were performed for the elementary FCL unit to find the generating aspects of the flux flow resistance and the contact resistance. Current limiting and breaking performances were measured for the small model of the FCLCB that was constructed by connecting the elementary FCL unit with the relay contactor. It is confirmed that the apparent capability of the breaker unit is elevated by combination with the FCL unit. The FCL unit for the 6.6 kV power distribution systems was also designed.
[Show abstract][Hide abstract] ABSTRACT: The relationship between the critical current density and flux flow resistivity in a Bi2223 bulk for fault current limiter application was experimentally investigated. The distributions of J<sub>c</sub> and voltage along the longitudinal direction were measured as well as the transport current. As a result, it was found that the flux flow resistivity is higher at positions of lower critical current. Measured results were numerically analyzed to obtain an empirical expression for the flux flow resistivity as a function of the critical current density, accumulated Joule heat and transport current.