Sometimes adding more ground rods and pipes won’t do achieve anything to bring the bottom resistance down in high resistivity areas. Especially sometimes, adding more ground rods won’t do anything whatsoever to bring the resistance down (the resistance stays precisely the same).
An excellent idea of soil resistivity and related testing is very important. Some guidelines should be established for the soil testing. Similarly the testing and spacing to ascertain the soil resistivity with depth is very important in particular when deep grounding/earthing elements will be used.
A better than acceptable ground resistance would modify the safe operation of power system. Several various methods ended up utilized for yesteryear to reduce the grounding resistance with the grounding system. Methods include enlarging the grounding/earthing grid, connecting the principle grounding grid having an external grounding grid, increasing the burial depth of the grounding grid, utilizing natural grounding object including 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 but that does not always mean they will work with no correct soil resistivity testing or proper evaluation and without assortment of acceptable data to justify their application. Actually, in the specific soil environment, 2 or more methods may very well be to decrease the grounding resistance effectively.
The method to incorporate deep vertical grounding electrodes to the grounding grid is very effective in substations with small area. Using this method can use the low-resistivity soil layer and take away the high resistivity soil at the surface affected by freezing and occasional temperature. So that you can limit 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 strategy is also suffering from cost.
One efficient method to slow up the earthing resistance of substation is with deep ground wells electrodes. Several kinds of deep ground wells exist: As an example it is possible to drill 150 mm ground well and go 50 meters to 85 meters deep or even more in the earth and soon you reach moist soil ground water or limestone… The ground well is filled with bentonite material and non-corrosive material to improve resistivity.
To get your house this kind of grounding you may need also to depend upon enhanced or maybe more advanced grounding program in order to calculate correctly the grounding resistance since programs such as ETAP or SKM would not have the required chance to do these calculations for the reason that grounding resistance of the equivalent model is not 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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