Fault current analysis for a superconducting 1 kA YBCO cable

Abstract

Superconducting cables can be used to transport large amounts of energy with small losses in considerably smaller volume compared to the conventional ones. The first YBCO cable demonstrations are under development and they are expected to outperform BSCCO cables. In the design work, the temperatures in the YBCO cables need to be simulated under any fault current conditions. In this paper, the temperature distribution in a 1 kA YBCO-cable was computed with various fault currents in order to study the thermal stability of the cable. The fault current is shared between the layers of superconducting YBCO tape and the copper shunt. FEM models were used to determine simultaneously both the current density and the temperature distributions of the cable as a function of time. Adiabatic conditions were assumed in order to obtain an upper limit for the temperature. According to the model, the copper core was able to absorb most of the heat. The cable maintained the thermal stability during 1 s with 10 and 20 kA (rms) fault currents. With 30 and 40 kA fault currents the cable was predicted to quench.