|Description||Sometimes adding more ground rods and pipes is not going to do achieve everything to bring the ground resistance down in high resistivity areas. Especially sometimes, adding more ground rods won't a single thing to bring the resistance down (the resistance stays exactly the same).|
A great understanding of soil resistivity and related tests are extremely important. Some guidelines should be established for your soil testing. Similarly the testing and spacing to ascertain the soil resistivity with depth is very important in particular when deep grounding/earthing elements shall be used.
An increased than acceptable ground resistance would affect the safe operation of power system. Several various methods have been used in the past to decrease the grounding resistance with the grounding system. Methods include enlarging the grounding/earthing grid, connecting the key grounding grid having 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 around the grounding grid with low resistivity materials and chemicals.
These procedures are suitable for different geographical situations however that doesn't imply they are going to work without having a correct soil resistivity testing or proper evaluation and without collection of acceptable data to warrant their application. In fact, in a specific soil environment, two or more methods can be viewed as to lower the grounding resistance effectively.
The process to provide deep vertical grounding electrodes for the grounding grid is extremely efficient at substations with small area. This technique can utilize the low-resistivity soil layer and get rid of the high resistivity soil near the surface afflicted with freezing and low temperature. In order to reduce the grounding resistance, the explosive grounding technique was proposed to decrease the grounding resistance of grounding grids in high resistivity area. The look at the explosive grounding technique just like any grounding method is also afflicted with cost.
One efficient approach to reduce the earthing resistance of substation is to apply deep ground wells electrodes. Several types of deep ground wells exist: For instance you'll be able to drill 150 mm ground well and go 50 meters to 85 meters deep or maybe more in the earth before you reach moist soil ground water or limestone... The soil well is full of bentonite material and non-corrosive material to enhance resistivity.
To carry out this sort of grounding you'll need and to depend upon enhanced or higher advanced grounding enter in order to calculate correctly the grounding resistance since programs like ETAP or SKM would not have the necessary chance to do these calculations for the reason that grounding resistance of the equivalent model can not be easily calculated. The grounding resistance of your deep ground well may be calculated by numerical analysis program according soil model. The SES program works extremely well.
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|Created||22 Dec 2019|
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