Walsh Wentworth posted an update 1 year, 10 months ago
Sometimes adding more ground rods and pipes will not likely do achieve almost anything to bring the soil resistance down in high resistivity areas. Especially sometimes, adding more ground rods won’t do just about anything to get the resistance down (the resistance stays the identical).
A fantastic understanding of soil resistivity and related exams are extremely important. Some guidelines should be established for that soil testing. Similarly the testing and spacing to look for the soil resistivity with depth is essential particularly if deep grounding/earthing elements shall be used.
A better than acceptable ground resistance would get a new safe operation of power system. Several various methods was applied in days gone by to reduce the grounding resistance in the grounding system. Methods include enlarging the grounding/earthing grid, connecting the main grounding grid with an external grounding grid, increasing the burial depth of the grounding grid, utilizing natural grounding object such as steel foundations of structures, adding long vertical grounding electrodes or pipes, and changing the soils throughout the grounding grid with low resistivity materials and chemicals.
These methods are compatible with different geographical situations but that does not always mean they’re going to work without a correct soil resistivity testing or proper evaluation and without collection of acceptable data to warrant their application. In reality, within a specific soil environment, several methods can be viewed as to reduce the grounding resistance effectively.
The method to include deep vertical grounding electrodes towards the grounding grid is incredibly good at substations with small area. This process can use the low-resistivity soil layer and get rid of the high resistivity soil at the surface affected by freezing and low temperature. As a way to limit the grounding resistance, the explosive grounding technique was proposed to diminish the grounding resistance of grounding grids in high resistivity area. The evaluation of the explosive grounding technique as with any grounding method is also suffering from cost.
One efficient strategy to reduce the earthing resistance of substation is with deep ground wells electrodes. Several kinds of deep ground wells exist: For example you can drill 150 mm ground well and go 50 meters to 85 meters deep or more on your lawn unless you reach moist soil ground water or limestone… The ground well is stuffed with bentonite material and non-corrosive material to enhance resistivity.
To do such a grounding you need and also to count on enhanced or even more advanced grounding enter in to calculate correctly the grounding resistance since programs like ETAP or SKM would not have the mandatory chance to do these calculations as the grounding resistance in the equivalent model cannot be easily calculated. The grounding resistance of an deep ground well might be calculated by numerical analysis program according soil model. The SES application can be utilized.
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