Tips about how Should We Reduce Ground Resistance?
Sometimes adding more ground rods and pipes will not do achieve almost anything to bring the ground resistance down in high resistivity areas. Especially sometimes, adding more ground rods will not likely a single thing to get the resistance down (the resistance stays exactly the same).
A fantastic knowledge of soil resistivity and related tests are essential. Some guidelines ought to be established for the soil testing. Similarly the testing and spacing to look for the soil resistivity with depth is essential in particular when deep grounding/earthing elements will be used.
A greater than acceptable ground resistance would affect the safe operation of power system. Several various methods had been 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 with an external grounding grid, improving the burial depth with 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 doesn't imply they will work with out a correct soil resistivity testing or proper evaluation and without number of acceptable data to warrant their application. In reality, within a specific soil environment, several methods can be considered to decrease the grounding resistance effectively.
The technique to provide deep vertical grounding electrodes towards the grounding grid is quite effective in substations with small area. This method can utilize the low-resistivity soil layer and get rid of the high resistivity soil nearby the surface affected by freezing and low temperature. To be able to decrease 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 as with all grounding technique is also suffering from cost.
One efficient approach to limit the earthing resistance of substation is to apply deep ground wells electrodes. Various kinds of deep ground wells exist: For instance you can drill 150 mm ground well and go 50 meters to 85 meters deep or even more in the earth unless you reach moist soil ground water or limestone... The floor well is full of bentonite material and non-corrosive material to improve resistivity.
To do this kind of grounding you need and to depend on enhanced or higher advanced grounding enter in to calculate correctly the grounding resistance since programs for example ETAP or SKM would not have the mandatory chance to do these calculations since the grounding resistance with the equivalent model is not easily calculated. The grounding resistance of an deep ground well may be calculated by numerical analysis software program according soil model. The SES application can be utilized.
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