Neural voltage and current dependency on fault impedance value in medium voltage networks

Medium voltage (MV) networks, by their nature, are located between transmission lines and distribution - low voltage lines. Typically, MV networks were held unearthed Le. isolated due to the superiority of isolated networks in terms of availability. Nevertheless, with the increase of underground cables share in the overall MV network's length, the capacitive earth-fault currents exceed permissive thresholds imposed by national regulations, therefore earthing of networks becomes imperative. Measurement of neutral to earth voltage and neutral current is of crucial importance for correct relay protection operation during transient and stable earth-faults. Special attention will be given to the neutral to earth voltage dependence on fault impedance value.