Results of the research on global earthing systems: A contribution to the problem of their identification

The paper presents a study on the factors that can have influence on the rise of a Global Earthing System. The first part of the work deals with: - the definition of proximity, interconnection and quasi-equipotential; - the influence of the presence of HV/MV stations on the dangerous voltages and on the permissible voltage limits; - the dependence of the hazardous condition for persons on the different kind of fault; - the effects on safety of the coexistence of HV, MV and LV systems. In the second part, starting from the discussion on the themes above-mentioned and on the results of the studies, measurement campaigns and simulations on interconnected earthing systems done in the last fifteen years, three simple models for the simulation of the behavior of an extended interconnection of earth electrodes during different fault events are proposed. The models allows the evaluation of the maximum earth potential rise at every possible fault location and for every possible fault event and can be used for the identification a Global Earthing System in a given area.