AC losses in multifilamentary low AC loss Bi(2223) tapes with novel interfilamentary resistive carbonate barriers

For the AC application of multifilamentary BSCCO-Tapes at 50-60 Hz in power cables and transformers, the main components of the AC losses are hysteres is losses in the filaments and coupling current losses in the normal conduc ting matrix. Coupling losses can be reduced by enhancing the matrix resitiv ity and by applying a twist to the filaments. We developed a novel multifil amentary BSCCO tape in an Ag matrix with resistive SrCO3 barriers between t he filaments to enhance the transverse resistivity. AC loss measurements on two different types of conductor designs are shown in this paper. In the f irst series of conductors the barrier forms something like a honeycomb stru cture in the cross-section between the filaments (DCB tapes). From this con ductor type a series with Ag and AgAu(8wt%) matrix was prepared. The AgAu w as chosen to increase the matrix resistivity compared to Ag, In the second series of tapes the conductor structure is similar to a Rutherford cable (R BB tapes). Six bundles of 7 filaments are stacked round a central SrCO3 cor e and deformed to a tape. All types of tapes have been twisted with a twist length down to 7.5 mm. In the AC transport current loss measurements we fi nd a loss reduction in the RBB tapes due to the fact that the filaments in these tapes are nearly fully transposed. In external AC fields loss reducti ons in parallel as well as in perpendicular fields are found in both conduc tor series due to the decoupling of filaments.