How to use the clamp meter grounding resistance meter
The grounding resistance test method follows Ohm's law. The three-pole and four-pole potential drop test method is one of the commonly used test methods, commonly known as the ground pile method. Disconnect the grounding system and equipment under test before measuring. Under normal circumstances, when testing a single ground electrode by the three-pole grounding measurement method, the auxiliary electrode 3 can be placed at a distance of 31 meters from the ground electrode to be tested, and the auxiliary electrode 2 can be placed at a distance of 19 meters from the ground electrode (62% is the recommended point). But for large ground systems, the distance needs to be increased. During the test, accurate measurement can be performed by adjusting the position of the auxiliary pole 2 and finding the equipotential area. The four-pole method can remove the resistance of the test leads, which can achieve more accurate measurement than the three-pole method, and is suitable for low-resistance measurement.
The generally recommended selective test method is essentially not much different from the ground stake method. The grounding electrode is set according to the same requirements, but only because the current clamp is used, so there is no need to disconnect the equipment and the grounding electrode.
For the clamp ground resistance meter, it must be determined that there must be a ground loop before use. The ground stake method is to artificially construct a ground loop between the ground electrode and the earth. If the ground electrode under test is already in a natural ground loop, a direct measurement can be made with a ground resistance clamp meter. If it is indoors, and the grounding of the equipment is through the grounded neutral wire, connected to the grounding busbar, and then grounded by the main grounding electrode, a comprehensive grounding resistance tester is required. You can first use the double clamp method or test the loop impedance of the grounding neutral line of the equipment to judge the connection performance, then test the grounding resistance of the main grounding electrode by the three-level method, and then use the AC and DC equipotentiality to measure the grounding access point and the main grounding of the equipment. resistance between the poles. Only in this way can we comprehensively judge the quality of equipment grounding.
