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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 will not do anything whatsoever to get the resistance down (the resistance stays the identical).
A fantastic comprehension of soil resistivity and related tests are essential. Some guidelines should be established for that soil testing. Similarly the testing and spacing to discover the soil resistivity with depth is vital particularly when deep grounding/earthing elements shall be used.
A better than acceptable ground resistance would impact the safe operation of power system. Several various methods have been used in yesteryear to diminish the grounding resistance in the grounding system. Methods include enlarging the grounding/earthing grid, connecting the primary grounding grid by having an external grounding grid, enhancing 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.
They are suitable for different geographical situations but that doesn't imply they are going to work without having a correct soil resistivity testing or proper evaluation and without collection of acceptable data to warrant their application. In fact, inside a specific soil environment, 2 or more methods can be viewed as to reduce the grounding resistance effectively.
The method to incorporate deep vertical grounding electrodes to the grounding grid is quite great at substations with small area. Using this method can use the low-resistivity soil layer and remove the high resistivity soil close to the surface afflicted with freezing and low temperature. So that you can slow up 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 as with every grounding technique is also suffering from cost.
One efficient method to decrease the earthing resistance of substation is to use deep ground wells electrodes. Several types of deep ground wells exist: For example you are able to 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 further improve resistivity.
To get your house this kind of grounding you'll need and then to depend upon enhanced or higher advanced grounding put in order to calculate correctly the grounding resistance since programs for example ETAP or SKM will not have the mandatory chance to do these calculations for the reason that grounding resistance with the equivalent model cannot be easily calculated. The grounding resistance of a deep ground well can be calculated by numerical analysis application according soil model. The SES software program can be utilized.
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| Bryan Combs |
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