Influence of Repeated Mechanical Stresses on AC Losses in Multi-Filamentary Bi2223/Ag-Sheathed Wires

Influence of repeated mechanical stresses/strains on AC losses (transport current losses and magnetization losses) in two kinds of multi-filamentary Bi2223/Ag-sheathed wires (twisted and non-twisted) for AC power cables was experimentally investigated. Repeated uni-axial tensile stresses/strains were applied to the wires in the longitudinal direction and the AC losses were measured electrically at 77.3 K. It was found that the influence of the repeated mechanical stresses/strains on the AC losses was different in the twisted and non-twisted wires. In the paper it is shown that the differences can be characterized by assuming that there are two kinds of critical currents of a sample wire, overall critical current across whole length of the sample wire and local critical current within the sample. Those critical currents are affected differently by the repeated mechanical stresses/strains. It is also shown that differences in manners of relations between the AC loss characteristics and the two kinds of critical currents can be explained assuming that different types of defects are caused by the repeated stresses in the two kinds of the wires.