Acceptable Risk Zone for Grounding Systems in Distribution MV/ LV Substations

The paper concerns the analysis and simulation of the behavior of the total ground potential around the grounding systems of the installation-on-pole (PTP and disconnector) and MV/LV substations in order to define and quantify the best possible safety distances in terms of “acceptable risk” around the grounding systems. The analysis was conducted by adopting the Maxwell method for the analytical simulation of the grounding systems. By the analysis of the databases of the main Italian distribution system operator, each one with over than 300,000 data about the Italian grounding systems, the paper proposes a macroscopic result to define an “acceptable risk zone” by taking into consideration a weighted average value for the fault current and a medium value for the ground resistivity.