What is the qualified value of the grounding resistance in the measurement of ground resistance?
Lightning protection grounding:Lightning grounding resistance is less than 10 ohm; grounding lightning induction device, the grounding resistance is less than 10 ohm; high potential to prevent the intrusion of the iron pin insulator arrester, metal cable sheath and overhead line terminal rod on the grounding resistance is less than 10 overhead metal pipes in Europe; the building should be every 25 meters, the ground once, the grounding resistance is less than 20 euro. But the explosion risk, such as the introduction of low-voltage overhead lines directly into the building, needs to be taken measures: closed valve type arrester, the total grounding resistance is not greater than 5 ou.
Repeated earthing:According to the relevant provisions, the low-voltage power grid directly grounded in the terminal and along the trunk and branch line of overhead lines every kilometer zero line should be repeated grounding, each repeat grounding resistance should be less than 10 ohm; in the grounding resistance of 10 ohms to allow for the occasion, every repeat the grounding resistance should be less than 30 ohm, but shall not be less than 3 repeat grounding.
Work earthing (zero protection), protective earthing:In the 380/220 volt low voltage system, the earth current is very small, generally not more than a few, so the provisions of the resistance is not greater than 4 ohms, when the capacity is below 100 thousand volts, the ground resistance can be extended to no more than 10 ohms.
Below 1000V below the neutral point, the grounding resistance of the system is less than or equal to 4 ohm, and the repeated earth resistance is less than or equal to 10 ohm.2, the voltage below 1000V neutral ungrounded system, the general provisions of the grounding resistance of 4 euro.Therefore, according to the actual installation experience, the ground resistance of the street lighting system should be less than or equal to 4 euro.Single point grounding is usually used to test the grounding resistance of the instrument in the following style:
