pepperwood67 posted an update 1 month ago
Sometimes adding more ground rods and pipes will not do achieve anything to bring the floor resistance down in high resistivity areas. Especially sometimes, adding more ground rods will not likely do anything whatsoever to bring the resistance down (the resistance stays the identical).
A good knowledge of soil resistivity and related testing is extremely important. Some guidelines must be established for the soil testing. Similarly the testing and spacing to ascertain the soil resistivity with depth is essential particularly if deep grounding/earthing elements shall be used.
An increased than acceptable ground resistance would impact the safe operation of power system. Several various methods have been utilized for the past to decrease the grounding resistance in the grounding system. Methods include enlarging the grounding/earthing grid, connecting the main grounding grid having an external grounding grid, enhancing 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 around the grounding grid with low resistivity materials and chemicals.
These techniques are suitable for different geographical situations but that doesn’t imply they’re going to work with out a correct soil resistivity testing or proper evaluation and without variety of acceptable data to warrant their application. Actually, in a specific soil environment, 2 or more methods may very well be to diminish the grounding resistance effectively.
The technique to include deep vertical grounding electrodes on the grounding grid is quite good at substations with small area. Using this method can utilize low-resistivity soil layer and get rid of the high resistivity soil near the surface suffering from freezing and occasional temperature. To be able to reduce the grounding resistance, the explosive grounding technique was proposed to decrease the grounding resistance of grounding grids in high resistivity area. The evaluation of the explosive grounding technique just like any grounding way is also afflicted with cost.
One efficient way to decrease the earthing resistance of substation is to apply deep ground wells electrodes. Several types of deep ground wells exist: As an example you are able to drill 150 mm ground well and go 50 meters to 85 meters deep or more in your yard before you reach moist soil ground water or limestone… The floor well is filled with bentonite material and non-corrosive material to improve resistivity.
To get your house this sort of grounding you may need and also to depend upon enhanced or more advanced grounding program in to calculate correctly the grounding resistance since programs such as ETAP or SKM do not have the mandatory capacity to do these calculations because the grounding resistance from the equivalent model can not be easily calculated. The grounding resistance of an deep ground well may be calculated by numerical analysis program according soil model. The SES application can be used.
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