Bird Persson posted an update 9 months ago
Sometimes adding more ground rods and pipes will not do achieve almost anything to bring the soil resistance down in high resistivity areas. Especially sometimes, adding more ground rods won’t do anything to take the resistance down (the resistance stays exactly the same).
An excellent knowledge of soil resistivity and related testing is essential. Some guidelines must be established for that soil testing. Similarly the testing and spacing to look for the soil resistivity with depth is vital particularly when deep grounding/earthing elements will probably be used.
A higher than acceptable ground resistance would impact the safe operation of power system. Several various methods was applied to earlier times to diminish the grounding resistance of the grounding system. Methods include enlarging the grounding/earthing grid, connecting the primary grounding grid having an external grounding grid, enhancing 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 around the grounding grid with low resistivity materials and chemicals.
They are compatible with different geographical situations however that does not always mean they are going to work with no correct soil resistivity testing or proper evaluation and without assortment of acceptable data to warrant their application. Actually, inside a specific soil environment, two or more methods can be viewed as to diminish the grounding resistance effectively.
The process to include deep vertical grounding electrodes to the grounding grid is very good at substations with small area. This technique can make use of the low-resistivity soil layer and get rid of the high resistivity soil near the surface afflicted with freezing and occasional temperature. So that you can limit the grounding resistance, the explosive grounding technique was proposed to diminish the grounding resistance of grounding grids in high resistivity area. The look at the explosive grounding technique just like any grounding technique is also affected by cost.
One efficient approach to slow up the earthing resistance of substation is with deep ground wells electrodes. Several kinds 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 the earth until you reach moist soil ground water or limestone… The soil well is loaded with bentonite material and non-corrosive material to enhance resistivity.
To carry out this sort of grounding you will need and then to depend upon enhanced or higher advanced grounding enter in to calculate correctly the grounding resistance since programs such as ETAP or SKM do not have the mandatory chance to do these calculations for the reason that grounding resistance from the equivalent model can not be easily calculated. The grounding resistance of your deep ground well could be calculated by numerical analysis software program according soil model. The SES program can be utilized.
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