Fournier Horton posted an update 3 months, 1 week ago
Sometimes adding more ground rods and pipes will not do achieve anything to bring the bottom resistance down in high resistivity areas. Especially sometimes, adding more ground rods is not going to do anything to bring the resistance down (the resistance stays the identical).
A great knowledge of soil resistivity and related testing is extremely important. Some guidelines must be established to the soil testing. Similarly the testing and spacing to look for the soil resistivity with depth is very important in particular when deep grounding/earthing elements will probably be used.
A greater than acceptable ground resistance would affect the safe operation of power system. Several various methods ended up applied in earlier times to lower the grounding resistance of the grounding system. Methods include enlarging the grounding/earthing grid, connecting the primary grounding grid with an external grounding grid, helping the burial depth in the grounding grid, utilizing natural grounding object such as 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 suitable for different geographical situations but that doesn’t imply they’re going to work with no correct soil resistivity testing or proper evaluation and without collection of acceptable data to justify their application. The truth is, within a specific soil environment, 2 or more methods may very well be to diminish the grounding resistance effectively.
The technique to provide deep vertical grounding electrodes on the grounding grid is quite great at substations with small area. This technique can utilize low-resistivity soil layer and remove the high resistivity soil at the surface afflicted with freezing and occasional temperature. To be able to decrease the grounding resistance, the explosive grounding technique was proposed to lower the grounding resistance of grounding grids in high resistivity area. The look at the explosive grounding technique as with every grounding method is also afflicted with cost.
One efficient method to reduce the earthing resistance of substation is to apply deep ground wells electrodes. Several types of deep ground wells exist: By way of example you are able to drill 150 mm ground well and go 50 meters to 85 meters deep or higher in the earth and soon you reach moist soil ground water or limestone… The soil well is full of bentonite material and non-corrosive material to improve resistivity.
To carry out this kind of grounding you need also to depend upon enhanced or maybe more advanced grounding program in order to calculate correctly the grounding resistance since programs like ETAP or SKM don’t have the mandatory capacity to do these calculations for the reason that grounding resistance in the equivalent model can’t be easily calculated. The grounding resistance of the deep ground well could be calculated by numerical analysis program according soil model. The SES application may be used.
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