Correlation between Worst Case Safety Conditions and Soil Resistivity under Power System Fault Conditions

J. Ma and F.P. Dawalibi (Canada)


Transmission and Distribution, Power Plant, Safety, Grounding, Body Current, Touch Voltage


This paper examines the correlation between worst case safety conditions and soil resistivity under power system fault conditions. For a simplified power system network, analytical expressions have been derived which clearly show the relation between safety and soil resistivity. It is interesting to see that neither the very low resistivity (close to zero -m) nor the very high resistivity (> 10000 -m) represents the worst case for human safety under power system fault conditions. Depending on system parameters, the worst case soil resistivity is generally on the order of a few hundred -m. For complicated realistic power system networks, computer modeling is carried out for the analysis and similar conclusions are reached. The findings described in this paper have not been published in the open literature.

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