A.c. losses in Bi-2223 tapes for power applications

Abstract

Improved measuring procedures and interpretation efforts have shown that the critical state model is fully applicable for describing the behaviour of HTS tapes for power applications. By this means, we could consistently analyse magnetic and transport measurements and study possible inhomogeneities and geometrical peculiarities in BSCCO-2223 tapes. Examples of such an analysis are given in this contribution. Losses in multistrand conductors require a more complex modellization and further development of the experimental procedures; the results of a.c. transport measurements on a 13 m long, multilayer, prototype conductor sample are also discussed here.

Current distribution and ac loss for a superconducting rectangular strip with in-phase alternating current and applied field

“…where I k is the current in the time k. Equation ( 11) yields much more accurate results of ∂ I A than using finite differences between consecutive time points. Indeed, according to the mean value theorem, there must exist some current between I k−1 and I k+1 where the derivative is exactly the right-side part of equation (11). Equation ( 11) cannot be used at the boundaries of a half cycle, I = ±I m , as ∂ I A is not continuous there.…”

“…Actually, the reduction of the ac loss is vital for the applicability of superconductor electrical technology [7,8]. The study of the ac loss is also interesting for material science, since in can be used for characterizing superconducting samples [9,10,11,12].…”

“…From a practical point of view, it is of fundamental importance to understand, predict and, eventually, reduce the energy loss (or ac loss) in the superconductor. The study of the ac loss is also interesting for material science, as it can be used to characterize superconducting samples [9][10][11][12]. Apart from its applications, the ac loss is the main alternating quantity under the simultaneous application of alternating current and field and, thus, its study is significant in itself.…”

Experimental study of the effect of filament orientation on transport and magnetic ac loss in Bi-2223/Ag multifilamentary tapes

“…Under transport conditions, the shell versus core division does not apply to individual filaments, because the whole filamentary zone represents the area that is step-by-step saturated by the transport current as the amplitude increases. It is probably the filament quality's dependence on the position that made this model also applicable to multifilamentary tapes [17].…”

Transport ac losses of multifilament Ag-sheathed Bi-2223 tapes with periodically arranged filaments in the configuration

“…The self-field hysteresis ac losses of mono-and multifilamentary tapes have been solved theoretically using the critical-state model [2]. The transport ac losses of multifilamentary tapes may be compared with those theoretically derived and many authors have presented ac loss data of twisted and untwisted multifilament tapes which fall between these two derived limits [3][4][5][6]. Points of inflection between these two limits have also been observed in experimental data, where the ac loss profile changes from the Norris ellipse corresponding to one I c to the ellipse corresponding to a lower I c [3,6].…”