Practical method for evaluating ground fault current distribution in station supplied by an unhomogeneous line

The paper presents an analytical procedure which enables a quick and, at the design stage, correct evaluation of the ground fault current distribution, for a fault in a substation supplied by a line coinposed of two or more unifoiin and different sections The advantages of the inethod are based on the simplicity and accuracy of the foimulae for solving uniform lumped parameter ladder circuits of any size and under any terminal conditions The formulae are obtained by applying the "geneial equations of the line reptesented by discrete parameters" on a specific electrical circuit formed by a transmission line giound wire during ground faults The paper also derives simple and exact expi essioiis for solving ladder circuits formed by the discretization of undergiound conductois which are in continuous contact with eaith (e g tlie sheaths of a cable, an interconnecting copper bui led in the soil, a pipeline, etc ) The cor1 ect pi ediction of the expected ground fault current parts in soil and neutral conductors IS of great importance in designing safe and economical substation grounding installations