Transport Loss Characteristics of the Bi-2223 Tapes in an External AC Magnetic Field

A Bi-2223 tape has been developed for power applications such as a fault current limiter, a power cable and a superconducting magnetic energy storage system (SMES). In such applications, the Bi-2223 tape carries time varying transport current and in addition experiences time varying external magnetic field. It is well known that the external magnetic field not only causes magnetization loss in the Bi-2223 tape, but also drastically increases transport loss due to a so-called "dynamic resistance". We developed an evaluation setup, which can measure transport loss in an external AC magnetic field. Using this equipment, we measured the dynamic resistances for various amplitudes and frequencies of external AC magnetic field perpendicular to the face in the tape. Simultaneously we investigated the effect of external AC field on transport loss with different experimental conditions. This paper describes test results and discussions on correlation between the dynamic resistance and the transport loss for various technical Bi-2223 tapes