Test of YBCO thin films based fault current limiters with a newly designed meander

To facilitate the up scaling of thin film based fault current limiters (FCL), a complete control of the localization of the dissipated power is needed. This control can be achieved by a new design where constrictions, which are regularly located along the YBCO/Au meander, have the aim of localizing and homogenizing this dissipated power at the beginning of a short circuit. To minimize the initial power peak, the resistivity of the constrictions has to be as small as possible whereas the resistivity of the connecting paths should be increased in order to lower the long-term power. We have tested these expected improvements on 5 kW (340 V, 16 A) FCL, on 2'' wafers, in AC conditions. The observed behavior of the FCL during short circuits, initiated at fault angles, confirm that the dissipated power is minimized and distributed, in a controlled way, along the meander. Finally we present measurements of the self-restoring time of the FCL and test on a 10 kW FCL made of two wafers connected in parallel.