Quench Behavior of Isotropic Strand Made From Coated Conductors With Overcurrent at Power Frequency

This paper presents the quench behavior of isotropic strands made from second-generation (2G) coated conductors (CCs) subjected to overcurrent at power frequency and liquid nitrogen, in order to evaluate their prospects for power applications. The isotropic strands with high current capacity, consisting of CCs in parallel, were prepared by putting them into different metal sheaths using industrial soldering techniques and drawing as well as extrusion processes. Current over the critical current was supplied to the sample strands, with a duration of 700 ms, at 77 K. Profiles of the voltage, current, and temperature in the sample strand were recorded during the pulsing overcurrent test. Based on the U(t) and I(t) curves, the resistance of sample strands and phase angle between voltage and current were also obtained. After each pulsing current, the critical current and n-values of the sample strands were retested. The results show that quench characteristics of the sample strands with different sheaths are very different from each other. Additionally, the sample strand fabricated by stainless-steel sheath has stronger current-limited ability than the copper or aluminum sheaths.