Sometimes adding more ground rods and pipes won't do achieve everything to bring the soil resistance down in high resistivity areas. Especially sometimes, adding more ground rods is not going to a single thing to bring the resistance down (the resistance stays the same).
A fantastic knowledge of soil resistivity and related tests are essential. Some guidelines should be established to the soil testing. Similarly the testing and spacing to ascertain the soil resistivity with depth is essential especially if deep grounding/earthing elements are going to be used.
A better than acceptable ground resistance would get a new safe operation of power system. Several various methods have been used in earlier times to lower the grounding resistance of the grounding system. Methods include enlarging the grounding/earthing grid, connecting the key grounding grid having an external grounding grid, improving the burial depth in the grounding grid, utilizing natural grounding object like steel foundations of structures, adding long vertical grounding electrodes or pipes, and changing the soils throughout the grounding grid with low resistivity materials and chemicals.
They are compatible with different geographical situations however that doesn't imply they'll work without a correct soil resistivity testing or proper evaluation and without assortment of acceptable data to warrant their application. Actually, inside a specific soil environment, a couple of methods can be considered to diminish the grounding resistance effectively.The method to add deep vertical grounding electrodes on the grounding grid is very great at substations with small area. This technique can utilize low-resistivity soil layer and eliminate the high resistivity soil near the surface suffering from freezing and low temperature. To be able to decrease the grounding resistance, the explosive grounding technique was proposed to reduce the grounding resistance of grounding grids in high resistivity area. The look at the explosive grounding technique just like any grounding method is also affected by cost.
One efficient strategy to reduce the earthing resistance of substation is with deep ground wells electrodes. Several kinds of deep ground wells exist: For example you can drill 150 mm ground well and go 50 meters to 85 meters deep or more in your yard and soon you reach moist soil ground water or limestone… The bottom well is filled with bentonite material and non-corrosive material to enhance resistivity.
In order to do this sort of grounding you may need and also to depend upon enhanced or maybe more advanced grounding enter in to calculate correctly the grounding resistance since programs such as ETAP or SKM do not have the specified power to do these calculations since the grounding resistance from the equivalent model can't be easily calculated. The grounding resistance of the deep ground well may be calculated by numerical analysis software program according soil model. The SES software program may be used.
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