The final webinar of the series on improving the quality and energy saving, which was held on 19 July 2016, was a seminar "How to make high-quality grounding?" Dmitry Krasnoborov, ZANDZ Techical center specialist was the lecturer.
During the webinar it was told how to calculate and set grounding for energy saving devices - namely, what factors affect the resistance of the grounding device and what the formula are used for its calculation. Also the information on the measures that should be applied to reduce grounding resistance was shared at the seminar. In addition, the lecturer gave examples of calculations of grounding for industrial buildings of factories, hospitals, supermarkets, stadiums, railway facilities and substations.
Navigation through the answers to the questions asked during the lecture:
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1. |
Is grounding resistance normalized to remove static electricity of the roof? |
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2 |
To organize a grounding device, the use of horizontal ground electrodes only is unacceptable. The main contribution to the drainage of the current to the ground is played by the vertical ground electrodes that are to be submerged in the ground below the freezing depth. In conditions of high soil resistivity, grounding device is designed according to the touch voltage. |
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3. |
Hello. Why do you set lightning rods on brick air ducts on the roof in your projects? Is the cost of ground electrodes not too high at the rate of 10 ohms, and decrease in resistance to 0.93 ohms? For transformer substation it is reasonable but in other cases - not a sure bet. |
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4. |
For what purposes do you consider grounding device during a webinar? |
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5. |
What do you think about active lightning rods? |
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6. |
I'v never seen it written that the ground electrode must be installed below the freezing depth. Where does it come from? 0.7 m from the surface and take into account the climatic factor is everything that is required by the regulatory documents. Ground electrode, in contrast to the water supply system or sewerage won't be broken when laying it in the freezing zone. |
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7. |
Why is a linear arrangement of vertical ground electrodes indicated in almost all projects? In fact, ground electrodes present themselves a parallel connection of resistances. If to use closed loops of the 3 elements, the resistance will be lower? |
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8. |
And if to measure the average soil resistivity at the design, then the resistance of the contour will be close to real? |
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9. |
Do I need geology and measurement of soil resistivity to calculate the contour? |
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10. |
In our area, in Krasnodar region, connection of 3 vertical ground electrodes 1.8 meters long in a triangle with the sides of 1.5 meters is 1.5-1.8 ohms, and the projects state installation of 6 elements in the line. |
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11. |
If the ground waters are oligohaline at the current flow, that is electrolytic process, maybe the environment is aggressive? |
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12. |
Tell us about the lightning rod on an air duct. |
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