Information on how Should We Cut down Ground Resistance?
Sometimes adding more ground rods and pipes is not going to do achieve something to bring the floor resistance down in high resistivity areas. Especially sometimes, adding more ground rods will not do anything to take the resistance down (the resistance stays the same).
An excellent knowledge of soil resistivity and related exams are vitally important. Some guidelines should be established for your soil testing. Similarly the testing and spacing to discover the soil resistivity with depth is important especially if deep grounding/earthing elements will probably be used.
A higher than acceptable ground resistance would modify the safe operation of power system. Several various methods had been applied to yesteryear to diminish the grounding resistance of the grounding system. Methods include enlarging the grounding/earthing grid, connecting the principle grounding grid by having an external grounding grid, increasing the burial depth from the grounding grid, utilizing natural grounding object like steel foundations of structures, adding long vertical grounding electrodes or pipes, and changing the soils across the grounding grid with low resistivity materials and chemicals.
These methods are suitable for different geographical situations but that does not always mean they are going to work without a correct soil resistivity testing or proper evaluation and without number of acceptable data to warrant their application. In fact, inside a specific soil environment, several methods can be viewed to diminish the grounding resistance effectively.
The process to include deep vertical grounding electrodes on the grounding grid is extremely good at substations with small area. This method can use the low-resistivity soil layer and get rid of the high resistivity soil close to the surface suffering from freezing and occasional temperature. To be able to reduce the grounding resistance, the explosive grounding technique was proposed to lower the grounding resistance of grounding grids in high resistivity area. The evaluation of 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 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 on your lawn until you reach moist soil ground water or limestone... The bottom well is stuffed with bentonite material and non-corrosive material to improve resistivity.
To carry out this kind of grounding you may need and then to count on enhanced or maybe more advanced grounding put in to calculate correctly the grounding resistance since programs like ETAP or SKM would not have the specified chance to do these calculations for the reason that grounding resistance with the equivalent model cannot be easily calculated. The grounding resistance of the deep ground well might be calculated by numerical analysis program according soil model. The SES application can be used.
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