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Ground resistance is calculated on the basis of standard templates and formulas. The obtained data allow to get optimal variant of ready grounding. Predesign is necessary because at small or big indicator of resistance the grounding device will not work.
It is required to you
- - calculation formulas;
- - paper;
- - calculator;
- - pencil;
- - summary table of unit resistance of soil.
Instruction
1. Calculate ground resistance for several electrodes by the following formula: R = R1/KiN, where R1 – resistance of one electrode, Ki – utilization coefficient, N – quantity of single electrodes in grounding device. When performing this calculation it is not necessary to consider contribution of the grounding conductor acting as the connector.
2. Based on the same basic data, as when calculating grounding for several electrodes, carry out calculation of quantity of electrodes. Use the following formula: N = R1/KiR, State Duma R1 – resistance of one electrode, R – resistance necessary for functioning of the multielectrode ground wire (the size received in the previous calculation), Ki – utilization coefficient.
3. Round the received result of necessary quantity of electrodes towards increase.
4. Connect electrodes among themselves, and then to object for which the grounding device by means of copper rolled wire or steel strip is intended. For copper the optimum section of the conductor 70 mm2, for steel – 160 mm2 are considered.