3-D finite element simulations of strip lines in a YBCO/Au fault current limiter

Geometrical aspects of the design of fault current limiters (FCL) have a great impact on their performances. Recently, the University of Geneva have made certain optimizations by splitting the FCL into many small dissipative lengths in order to achieve a distributed transition along the device. For this paper, we have performed new 3D finite element method (FEM) simulations for studying the behavior of strip lines of a YBCO/Au FCL in an AC nominal use (sinusoidal current at industrial frequency) up to 3I(c). The very large aspect ratio of the device needs a particular attention to the modeling and meshing process. The numerical results show that presence of sharp corners can influence the performance of the device. Due to the high value of the electric field in these areas, the local losses are much higher than in the case of smooth corners, and this may lead to burning and cracking the wafer. Irreversible damage experiments have confirmed these locations. In this paper we proposed new geometries, taking into account the length of the connecting path and the corners optimization in order to decrease the risk of very high localized losses in the meander.