Numerical Simulation of AC Current Limiting by Bulk Bi-2212 Ceramic and 2G YBCO Tapes

Second generation YBCO tapes have extremely high (~10000) geometric aspect ratios (width to thickness), which require huge computer resources and thus renders the simulation of fault current limiters (FCLs) based on them very difficult. In this paper we offer a solution to the aforementioned problem by assuming a linear scaling of the thermal and electrical properties with the geometrical size. The results obtained in proprietary software are in very good agreement with those from commercial FEM software. We also compare the limiting properties of YBCO and BSCCO, and find that in order to enable BSCCO to carry the same rated current as YBCO, one needs more than 40 times larger volume of BSCCO. In addition, YBCO limits the current quicker and much more efficiently than BSCCO. Finally, we study the influence of defects on the current limiting properties of HTS tapes and find that defects lead to stronger heating and more non-uniform current and temperature distributions, especially in BSCCO.