AC losses in Bi-2223 tapes and in the 1-kA transmission line model

The authors present here results of their study of the 5 m long AC transmission line model with 1 kA current capability at 77 K. Primary attention was paid to the current characteristics and AC losses in individual tapes and in the core of the cable. The losses were measured as a function of AC magnetic field amplitude in various orientations of magnetic field with respect to the plane of the tape and filaments. Hysteresis losses were close to the losses in the AC regime, meaning that eddy current losses in tapes may be neglected when compared with hysteresis losses. They designed and constructed a 5 m long model of the AC transmission line using multifilamentary Bi-2223 tapes. The current core of the model contains 120 tapes for the forward line and 120 tapes for the backward line. AC losses in the current core were substantially greater than those seen in the individual tapes. The reason for this is related to a complex magnetic field distribution inside the current core.