Sometimes adding more ground rods and pipes won't do achieve everything to bring the ground resistance down in high resistivity areas. Especially sometimes, adding more ground rods will not a single thing to take the resistance down (the resistance stays the identical).
An excellent knowledge of soil resistivity and related exams are vitally important. Some guidelines should be established for that soil testing. Similarly the testing and spacing to discover the soil resistivity with depth is very important especially if deep grounding/earthing elements shall be used.
A better than acceptable ground resistance would affect the safe operation of power system. Several various methods was utilized for yesteryear to decrease the grounding resistance of the grounding system. Methods include enlarging the grounding/earthing grid, connecting the primary grounding grid with an external grounding grid, helping the burial depth in 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.
They are compatible with different geographical situations but that does not always mean they will work with out a correct soil resistivity testing or proper evaluation and without collection of acceptable data to justify their application. The truth is, in a specific soil environment, two or more methods can be viewed as to diminish the grounding resistance effectively.
The technique to provide deep vertical grounding electrodes for the grounding grid is very good at substations with small area. Using this method can use the low-resistivity soil layer and eliminate the high resistivity soil near the surface impacted by freezing and low temperature. So that you can decrease 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 all grounding method is also afflicted with cost.
One efficient strategy to slow up the earthing resistance of substation is to apply deep ground wells electrodes. Several kinds of deep ground wells exist: As an example it is possible to drill 150 mm ground well and go 50 meters to 85 meters deep or higher in the ground before you reach moist soil ground water or limestone... The ground well is stuffed with bentonite material and non-corrosive material to improve resistivity.
To get your house such a grounding you will need also to rely on enhanced or maybe more advanced grounding program in to calculate correctly the grounding resistance since programs including ETAP or SKM do not have the mandatory power to do these calculations since the grounding resistance with the equivalent model can't be easily calculated. The grounding resistance of a deep ground well can be calculated by numerical analysis program according soil model. The SES software program can be utilized.
For details about bot giam dien tro dat please visit webpage: look at this.
|