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  • McCallum posted an update 6 months, 2 weeks ago

    Sometimes adding more ground rods and pipes will not likely do achieve everything to bring the ground resistance down in high resistivity areas. Especially sometimes, adding more ground rods will not likely a single thing to take the resistance down (the resistance stays the same).

    A fantastic comprehension of soil resistivity and related exams are very 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 important especially if deep grounding/earthing elements are going to be used.

    An increased than acceptable ground resistance would impact the safe operation of power system. Several various methods ended up applied in earlier times to reduce the grounding resistance of the grounding system. Methods include enlarging the grounding/earthing grid, connecting the primary grounding grid with the external grounding grid, helping the burial depth in the grounding grid, utilizing natural grounding object like 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 however that does not mean they will work with no correct soil resistivity testing or proper evaluation and without variety of acceptable data to warrant their application. In fact, in a specific soil environment, several methods can be viewed to lower the grounding resistance effectively.

    The strategy to incorporate deep vertical grounding electrodes for the grounding grid is very good at substations with small area. This technique can make use of the low-resistivity soil layer and get rid of the high resistivity soil at 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 any grounding method is also impacted by cost.

    One efficient strategy to reduce the earthing resistance of substation is to apply deep ground wells electrodes. Various kinds deep ground wells exist: As an example you can drill 150 mm ground well and go 50 meters to 85 meters deep or maybe more in your yard and soon you reach moist soil ground water or limestone… The bottom well is loaded with bentonite material and non-corrosive material to boost resistivity.

    In order to do this type of grounding you need and to depend upon enhanced or maybe more advanced grounding program in order to calculate correctly the grounding resistance since programs for example ETAP or SKM don’t have the mandatory power to do these calculations because the grounding resistance from the equivalent model is not easily calculated. The grounding resistance of the deep ground well could be calculated by numerical analysis software package according soil model. The SES application can be used.

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