On the Influence of an Elevated Terrain on the Grounding Resistance of a Vertical Rod

In this paper, we analyze the grounding resistance of a vertical grounding rod located in an elevated terrain. Tall structures such as wind turbines and mobile phone base stations are often installed in remote and hilly locations to gain more power or to facilitate line of sight to end users. Those locations are at an increased risk of being struck by lightning due to the greater elevation compared to their surroundings. These hilly areas are usually very rocky with low soil conductivity. A proper grounding system is therefore of paramount importance. In this study, we analyze the influence of the elevated terrain considering a simplified cone and a truncated cone geometries as a function of the apex angle and top radius. It is shown that the grounding resistance can be significantly increased both, in the case of small mounds of only a few meters height, and in the case of a high hill or a mountain.