Magnetisation loss of BSCCO/Ag tape in uni-directional and rotating magnetic field

BSCCO/Ag tape superconductors are used in applications like power cables, transformers and motors/generators. In these applications, the superconductor is exposed to an alternating magnetic field that can have different orientations with respect to the tape. In applications like three-phase power cables and motors/generators, the tape is exposed to a rotating magnetic field. This paper describes a measurement setup to determine the magnetisation loss of short pieces (10 cm) of tape superconductor in uni-directional magnetic field with arbitrary direction and rotating magnetic field. Measurements are performed in liquid nitrogen using the pick-up coil technique. The sensitivity of the setup is sufficient to measure the magnetisation loss accurate down to magnetic field amplitudes of 0.5 mT, also in magnetic field applied parallel to the wide face of the conductor. A relation is verified that described the measured magnetisation loss in a rotating magnetic field with the results obtained for a uni-directional field. The magnetisation loss in a rotating magnetic field can be described, in most cases, with the component of the magnetic field perpendicular to the wide face of the tape conductor. Only when the parallel magnetic field component becomes more than two times larger than the perpendicular component that its contribution to the loss becomes significant. (C) 1999 Elsevier Science B.V. All rights reserved.