Computer Modeling of YBCO Fault Current Limiter Strips Lines in Over-Critical Regime With Temperature Dependent Parameters

We present the results of an advanced numerical model for fault current limiter (FCL) based on HTS thin films in which both thermal and electromagnetic aspects are taken into account. This model allows simulating the behavior of FCL in the over-critical current regime and we used it for studying strip lines of a YBCO/Au FCL on sapphire substrate. The electromagnetic and thermal equations have been implemented in finite-element method (FEM) software in order to obtain a model for investigating the comportment of the superconductor when the current exceeds I_c. In particular, materials equations have been implemented in order to simulate the electrical behavior of superconducting devices with strong over-critical currents. We report results of simulations in voltage source mode where currents largely exceed I_c. The global behavior of the FCL is compared with measurements, showing a good agreement. The use of FEM simulations offers the advantage to give access to local variables such as current density or temperature. Studies with this model can replace expensive experiments where very high current density might damage or destroy the FCL device.