AC loss characteristics of Bi-2223 HTS tapes under bending

Abstract

Superconductor is developed for applications in high-power devices such as power-transmission cables, transformers, motors and generators. In such applications, HTS tapes are subjected to various kinds of stress or strain. AC loss is also important consideration for many large-scale superconducting devices. In the fabrication of the devices, the critical current (Ic) of the high temperature superconductor degrades due to many reasons including the tension applied by bending and thermal contraction. These mechanical loads reduce the Ic of superconducting wire and the Ic degradation affects the AC loss of the wire. The Ic degradation and AC loss of Bi-2223 HTS tape were measured under tension and bending conditions at 77K and self-field. Moreover, the frequency characteristics of AC loss was measured at the 30–480Hz. As a result, self-field penetrates the deeper into the conductor at the lower frequency, which means higher self-field losses per cycle.