Numerical calculation of floating potentials for large earthing system

During the malfunction in the substation, there is danger that transferred potential from the earthing system area into the outer space may occur. This problem may be a limiting factor when calculating the earthing system. Generally, a danger from too high touch voltage occurs. Also, very large potential differences are possible. Calculation of the transferred potential in substation should be given special attention. Superposition procedures are often used in literature for calculation of transferred potentials with which it is needed to solve two or more large full systems of matrixes. Direct approach to forming and solving of modified matrix of potential coefficients by applying Galerkin´s procedures of weight residue in indirect method of boundary elements is considered in this paper. At the end of the article considered model was presented on example of calculation of a large steam power plant´s main ground electrode.