Advanced ac loss measurement methods for high-temperature superconducting tapes

Advanced ac loss measurement methods for superconducting tapes are describe d in detail and demonstrated on BSCCO/Ag (Bi2Sr2Ca2Cu3Ox with a Ag matrix) tapes in liquid nitrogen at 77 K. The aim of the measurements is to simulat e the situation of a tape conductor in an electric power application like a transformer coil or a power cable. In this class of devices the conductor is fed with an alternating transport current and simultaneously exposed to an alternating magnetic field. In many devices the magnetic field vector po ints in a single direction but in some devices such as three-phase power ca bles and motors the magnetic field rotates around the conductor. In all cas es described above an electromagnetic approach with pick-up coils and volta ge taps is used to measure the ac loss. This method enables a separate stud y of magnetization loss and transport current loss when both the magnetic f ield and transport current are present simultaneously. The magnetization lo ss measurement setup for unidirectional and rotating magnetic field is desc ribed. The transport current loss measurement setup is described, focusing on the suppression of cross effects of ac transport current and ac magnetic field that disturb accurate measurements. Finally several relevant example s of the results obtained are shown. (C) 2001 American Institute of Physics .