Study of self-field AC losses in mono and multi-filamentary Bi-2223 tapes for power applications

The self-field ac losses in mono, 7, 37 and 49 filament tapes near power frequencies are presented. Although the losses in a mono and 37 filament tape showed good agreement with those predicted for a 'strip' and 'elliptical' geometry, respectively, the measured losses in the 7 and 49 filament tapes could not be accurately described by the Norris equations. This difference in loss behaviour can be attributed to the inter-filament connectivity and inhomogeneous J(c) distribution in the tapes. Non-linear inductance variation, due to flux linkage with the measuring leads, with applied current, is compared to a model for a homogeneous elliptical conductor and its significance to the corresponding measured ac losses is also discussed.