Fournier Horton posted an update 2 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 will not likely do anything whatsoever to bring the resistance down (the resistance stays the identical).
A fantastic understanding of soil resistivity and related exams are vitally important. Some guidelines ought to be established for your soil testing. Similarly the testing and spacing to determine the soil resistivity with depth is essential in particular when deep grounding/earthing elements will probably be used.
A higher than acceptable ground resistance would get a new safe operation of power system. Several various methods ended up utilized for the past to lower the grounding resistance with the grounding system. Methods include enlarging the grounding/earthing grid, connecting the main grounding grid by having an external grounding grid, increasing the burial depth from the grounding grid, utilizing natural grounding object including steel foundations of structures, adding long vertical grounding electrodes or pipes, and changing the soils round the grounding grid with low resistivity materials and chemicals.
These procedures are suitable for different geographical situations but that does not always mean they will work without a correct soil resistivity testing or proper evaluation and without variety of acceptable data to warrant their application. In reality, in a specific soil environment, several methods can be viewed as to diminish the grounding resistance effectively.
The technique to provide deep vertical grounding electrodes for the grounding grid is extremely great at substations with small area. This method can utilize the low-resistivity soil layer and eliminate the high resistivity soil close to the surface affected by freezing and low temperature. To be able to slow up 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 technique is also suffering from cost.
One efficient approach to limit the earthing resistance of substation is to use deep ground wells electrodes. Several types of deep ground wells exist: For instance you’ll be able to drill 150 mm ground well and go 50 meters to 85 meters deep or maybe more in the earth unless you reach moist soil ground water or limestone… The soil well is stuffed with bentonite material and non-corrosive material to improve resistivity.
In order to do this type of grounding you need and to depend upon enhanced or more advanced grounding put in to calculate correctly the grounding resistance since programs including ETAP or SKM would not have the specified capability to do these calculations as the grounding resistance of the equivalent model is not easily calculated. The grounding resistance of your deep ground well might be calculated by numerical analysis application according soil model. The SES program can be used.
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