The analysis of efficiency of shunt resistor during a single-phase earth fault using the two-port network theory

A simple and cheap reduction method to reduce a high residual current of the single-phase earth fault is to earth the affected phase in the transformer station. This paper describes a theoretical verification of efficiency of this method. The two-port network theory, used for the analysis of shunting method is explained, so that it could be applied to the resonant earthed neutral system. The assembled equivalent circuit and the mathematical description determine the conditions under which the method is possible to use. Parameters of elements of the equivalent circuit which influence the size of the faulty current in the fault point with the connected shunt in the substation were tested. The obtained diagrams show e.g. a dependence of a faulty current flows in the substation and a faulty current in the fault point, on the size of the network capacitive current, size of the fault resistance, size of the shunting resistance and etc. The paper deals with the steady state calculations.