Bird Blake posted an update 11 months, 2 weeks ago
Sometimes adding more ground rods and pipes won’t do achieve something to bring the soil resistance down in high resistivity areas. Especially sometimes, adding more ground rods won’t do just about anything to create the resistance down (the resistance stays the same).
A great understanding of soil resistivity and related exams are extremely important. Some guidelines must be established for your soil testing. Similarly the testing and spacing to discover the soil resistivity with depth is important particularly if deep grounding/earthing elements are going to be used.
A greater than acceptable ground resistance would impact the safe operation of power system. Several various methods ended up applied in earlier times to reduce the grounding resistance of the grounding system. Methods include enlarging the grounding/earthing grid, connecting the principle grounding grid with the external grounding grid, improving the burial depth with 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.
These procedures are suitable for different geographical situations however that does not necessarily mean they are going to work with no correct soil resistivity testing or proper evaluation and without number of acceptable data to warrant their application. In fact, in a specific soil environment, 2 or more methods can be considered to reduce the grounding resistance effectively.
The method to provide deep vertical grounding electrodes to the grounding grid is quite great at substations with small area. This method can make use of the low-resistivity soil layer and take away the high resistivity soil near the surface afflicted with freezing and low temperature. In order to slow up the grounding resistance, the explosive grounding technique was proposed to lower the grounding resistance of grounding grids in high resistivity area. The evaluation of the explosive grounding technique as with every grounding technique is also affected by cost.
One efficient way to limit the earthing resistance of substation is to use deep ground wells electrodes. Several kinds of deep ground wells exist: For instance you are able to drill 150 mm ground well and go 50 meters to 85 meters deep or maybe more in your yard before you reach moist soil ground water or limestone… The ground well is stuffed with bentonite material and non-corrosive material to improve resistivity.
To do this sort of grounding you may need and also to depend upon enhanced or more advanced grounding put in order to calculate correctly the grounding resistance since programs for example ETAP or SKM do not have the necessary power to do these calculations as the grounding resistance from the equivalent model can’t be easily calculated. The grounding resistance of an deep ground well can be calculated by numerical analysis application according soil model. The SES software program can be utilized.
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