McCallum Svenstrup posted an update 3 months, 2 weeks ago
Sometimes adding more ground rods and pipes is not going to do achieve anything to bring the ground resistance down in high resistivity areas. Especially sometimes, adding more ground rods won’t do anything whatsoever to create the resistance down (the resistance stays the identical).
An excellent idea of soil resistivity and related testing is vitally important. Some guidelines needs to be established for that soil testing. Similarly the testing and spacing to look for the soil resistivity with depth is essential especially if deep grounding/earthing elements shall be used.
A better than acceptable ground resistance would impact the safe operation of power system. Several various methods had been utilized for the past to lower the grounding resistance in the grounding system. Methods include enlarging the grounding/earthing grid, connecting the key grounding grid having an external grounding grid, improving the burial depth of 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.
They are compatible with different geographical situations however that does not necessarily mean they’re going to work with no correct soil resistivity testing or proper evaluation and without variety of acceptable data to justify their application. Actually, within a specific soil environment, several methods may very well be to decrease the grounding resistance effectively.
The strategy to incorporate deep vertical grounding electrodes towards the grounding grid is quite good at substations with small area. This process can utilize the low-resistivity soil layer and eliminate the high resistivity soil nearby the surface affected by freezing and occasional temperature. So that you can decrease the grounding resistance, the explosive grounding technique was proposed to reduce the grounding resistance of grounding grids in high resistivity area. The evaluation of the explosive grounding technique as with all grounding way is also suffering from cost.
One efficient strategy to limit the earthing resistance of substation is by using 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 maybe more in the ground until you reach moist soil ground water or limestone… The soil well is full of bentonite material and non-corrosive material to boost resistivity.
To do this kind of grounding you may need and also to rely on enhanced or higher advanced grounding put in to calculate correctly the grounding resistance since programs for example ETAP or SKM do not have the mandatory chance to do these calculations since the grounding resistance of the equivalent model can’t be easily calculated. The grounding resistance of an deep ground well may be calculated by numerical analysis software package according soil model. The SES application can be utilized.
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