A new technique for the measurement of AC loss in second-generation HTS tapes

The successful application of superconductivity to motors and other power system components depends on several factors. One of these involves characterization and minimization of the ac loss in the superconductor used for fabrication of the component. Previous electrical measurements of ac loss have been complicated by the presence of large, undesirable voltages due to stray inductances in the circuit. Their effect was minimized by the addition of a compensation circuit. We have developed a much simpler circuit that significantly reduces this problem to the extent that no compensation is necessary. We report on measurements of the ac loss of several commercial YBaCuO samples immersed in liquid nitrogen using this circuit. We also propose a definition for characterizing the quality of the tapes.