Shell- and core-type magnetic circuits effect in inductive SFCL under asymmetric faults

Asymmetric faults, namely phase to ground, are the most common in distribution grids. To adopt superconducting based technologies, namely superconducting fault current limiters (SFCL), utilities must be aware of the performance of these devices under such events, where a fault in e.g. a single phase may impact healthy ones. This performance is evaluated in this work in low voltage prototypes, namely three-phase inductive FCLs of transformer type where distinct magnetic circuits are applied, i.e. shell- vs. core-type laminations. In the latter, a conventional three-legged transformer core is used in the limiter, while in the former a five-legged core is employed, providing a low reluctance path for magnetic flux due to asymmetric faults, thus preventing it from affecting healthy phase(s). The performance of the devices is analysed under distinct asymmetric (and symmetric) faults, in order to provide guidelines for choosing the optimum configuration regarding also cost, weight and volume.