Case history: electronically controlled fault current limiters allow inplant switchgear to be interconnected

Design of fault current limiter using core with low initial permeability

“…FCL devices need to have certain features to prevent various fault currents effectively potentially occurring in the power grid. They must respond quickly to limit the first peak of fault currents at the first peak of fault current signal, exhibit low impedance in NMO (so that low energy dissipation and minimum voltage drop is expected), generate no unacceptable harmonics, have no sensor or similar control devices in order to increase the reliability of the whole system [7]. In addition to these features, the FCL must exhibit impedance which changes smoothly and gradually while in transition from the NMO into the fault mode and vice versa.…”