Study on stability evaluation and quench characteristics of non-stabilizing layer YBCO thin-film wire wound with the radius of curvature for application of SFCLS

The YBCO thin-film wire for superconducting fault current limiters shows promise with the following characteristics. (1) It has a high index value that enables a quick phase transition. (2) It has a high current density. (3) It experiences little change in the critical current in high magnetic fields. (4) It has varying quenching phenomena according to its stabilizing layers. Thus, it is being actively studied in many countries for application to power transmission and distribution systems. Based on current research results, this study examined the quenching occurrence trends in the YBCO thin-film wire that has been verified as a superconducting fault current limiter element and that has no stabilizing layers. This was done according to the wire's radii of curvature and in terms of the increase in its resistance, initial limited current, and quenching occurrence time. Five kinds of spiral-shaped formers were produced with the radii increasing from the minimum radius by 25%, taking into account their changing critical properties due to bending stress. The YBCO thin-film wire without stabilizing layers was wound around these formers. Then an alternating over-current was applied to the current limiting elements that were produced according to the radii of curvature. The resulting trends in resistance enhancement were examined to evaluate the stability of the produced current limiting elements. Finally, the produced current limiting elements' initial limited current and quenching occurrence time were observed at 90 K, 180K, and 250 K to evaluate the performance of the current limiting elements. (C) 2010 Elsevier B.V. All rights reserved.