Analysis of ground potential gradients around power substations

The substation ground potential rise due to a primary single-line-to-ground fault could be as high as 20 kV. A portion of this ground potential rise could be transferred to nearby plant ground grids through the earth, even if the two grounding grids are not bonded together. The percentage of this ground potential rise transfer depends on soil resistivity, distance between the power substation and the plant, and size of the substation itself. An accurate grounding system analysis program based on a two-layer soil model has been used to develop charts to illustrate the effect of these three variables on the potential gradients outside the power substation. The charts provide a guide for estimating the potential transferred to the plant ground due to the power substation ground potential rise without it being necessary to use a computer program