Svendsen Blake posted an update 1 year, 5 months ago
Sometimes adding more ground rods and pipes will not likely do achieve anything to bring the soil resistance down in high resistivity areas. Especially sometimes, adding more ground rods will not do anything to get the resistance down (the resistance stays the identical).
A good comprehension of soil resistivity and related exams are essential. Some guidelines should be established for that soil testing. Similarly the testing and spacing to ascertain the soil resistivity with depth is essential particularly if deep grounding/earthing elements are going to be used.
A higher than acceptable ground resistance would modify the safe operation of power system. Several various methods have been applied in earlier times to decrease the grounding resistance with the grounding system. Methods include enlarging the grounding/earthing grid, connecting the principle grounding grid with an external grounding grid, helping the burial depth of the grounding grid, utilizing natural grounding object for example steel foundations of structures, adding long vertical grounding electrodes or pipes, and changing the soils round the grounding grid with low resistivity materials and chemicals.
These techniques are suitable for different geographical situations however that doesn’t imply they’ll work without having a correct soil resistivity testing or proper evaluation and without assortment of acceptable data to justify their application. Actually, within a specific soil environment, a couple of methods can be viewed as to decrease the grounding resistance effectively.
The process to add deep vertical grounding electrodes on the grounding grid is incredibly efficient at substations with small area. This technique can utilize low-resistivity soil layer and eliminate the high resistivity soil close to the surface afflicted with freezing and low temperature. To be able to decrease the grounding resistance, the explosive grounding technique was proposed to decrease 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 method to limit the earthing resistance of substation is with deep ground wells electrodes. Several types of deep ground wells exist: As an example you can drill 150 mm ground well and go 50 meters to 85 meters deep or higher in the ground until you reach moist soil ground water or limestone… The floor well is filled with bentonite material and non-corrosive material to further improve resistivity.
To do this sort of grounding you need also to rely on enhanced or even more advanced grounding program in order to calculate correctly the grounding resistance since programs including ETAP or SKM will not have the specified chance to do these calculations because the grounding resistance from the equivalent model can not be easily calculated. The grounding resistance of a deep ground well can be calculated by numerical analysis software program according soil model. The SES application may be used.
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