Ground resistance tester how to measure grounding resistance

Grounding resistance tester method of use When some kind of abnormal situation occurs, if there is no grounding wire, it will be due to leakage and excessive voltage into the product damage, endangering personal safety, in order to prevent the occurrence of such problems, to ensure safety, the need for grounding wire. The metal bar that connects the metal casing of electrical products to the ground can play a role in discharging electricity. In order to prevent danger and ensure safety, grounding work should be carried out and the grounding resistance should be tested. Measurement of grounding resistance is to insert two grounding rods into the ground, between the grounding rods E and C, adding AC voltage, resulting in a current I, through the voltage generated between the E-C can be detected grounding resistance. The relationship between current I and voltage V is shown below, and the grounding resistance value can be calculated. However, the grounding resistance value R calculated by the above method. There is not only the grounding resistance of grounding electrode E, but also the grounding resistance of grounding electrode C. Therefore, it is necessary to establish a third grounding electrode between the grounding levels of E-C, and the value of grounding resistance RE of grounding electrode E can be calculated from the voltage Vp and current I between E-P. *There is also a resistive region at grounding electrode P. However, the AC constant current impedance of the supplied power supply is relatively high and has no effect on detection.　　　　Electrode method E (grounding wire) and auxiliary grounding rods P, C are spaced about 5-10 M apart and should be in a straight line.　　　　*When there is an obstacle that cannot be located in a straight line, a suitable angle between E-P and E-C can be used, generally within 30 degrees.　　　　When the grounding resistance point E (grounding wire) is already known to be nearby, it can be used to detect the unknown grounding resistance. The E terminal of the earth resistance meter is connected to the E point with a wire, and the P and C terminals are used as the first terminals, so that the resistance value can be detected between E and P.C. The display value contains the value of the known E point.　　　　*The resistance value at point E can be detected between E and P.C. The displayed value contains the resistance value at point E. The true RMS value should be calculated. The ground resistance at point E must be subtracted.　　　　*Sand, sand, frozen soil, need to be exposed to the soil surface; *Concrete, need to use an auxiliary net. The auxiliary net should be well sprinkled with water so as to make as much contact with the earth as possible for accurate detection.　　　　*Asphalt cannot be detected.