Evaluation of the grounding resistance reduction due to soil treatment for different grounding electrode configurations

Summary

There are many commercial applications and products to reduce the grounding resistance of a grounding system. One of them is the treatment of soil, where natural soil around the grounding electrodes is replaced by a low conductivity material in order to improve the performance of the configuration. Low conductivity materials are mainly composed by bentonite, a hygroscopic clay that allows the water to be retained for long periods. Generally, this application is employed for high resistivity soils to reduce the grounding resistance or for acid soils to reduce the corrosion on the electrodes. This paper presents results of two common geometries of grounding systems, vertical rod electrode and horizontal electrode, and two types of commercial soil treatments used in Chile. The aim of this work is to present the percentage of reduction of grounding resistance for two configurations when the soil treatment is used according to the recommendations of their manufacturers. To carry out the comparisons, three experimental setups were tested: one of them without soil treatment and the others with two different soil treatments. Electrodes were installed in the same area, taking care they do not interfere the influence area of each other. Grounding resistance was measured every three weeks during 10 months in order to consider wet and dry conditions of soil in the area. Setups were modelled in a finite elements software to compare results of measurements and to draw conclusions. Electric parameters of soil treatments were measured in laboratory to model the treatment into software. Results from measurements and simulation were in agreement, both showed similar reduction percentages for the period of the measurements. This percentage is close to 40% for vertical rod electrodes and between 20% and 40% for horizontal electrodes. The percentage reduction was similar for the two soil treatments employed in this study, in spite of they were from different manufacturers.

Additional informations

Authors

PEREIRA DA SILVA, PRESBÍTERO XAVIER

Keywords

Grounding systems, soil treatment, grounding resistance