H. Eckelmann et al., AC losses in multifilamentary low AC loss Bi(2223) tapes with novel interfilamentary resistive carbonate barriers, IEEE APPL S, 9(2), 1999, pp. 762-765
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.