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How to use ground resistance tester

AddTime:2021-01-26 17:10:28   Views:487  

When an abnormal situation occurs, if there is no grounding wire, the product will be damaged due to leakage and excessive voltage, which will endanger personal safety. In order to prevent such problems from occurring and ensure safety, a grounding wire is required. Metal electrical products The metal rod with the shell connected to the ground can discharge electricity. In order to prevent danger and ensure safety, grounding construction should be carried out and grounding resistance testing should be carried out.

The grounding resistance is measured by inserting two grounding rods into the ground, adding an AC voltage between the grounding rods E and C to generate a current I, and the grounding resistance can be detected by the voltage generated between the EC. The relationship between the current I and the voltage V As shown below, the ground resistance value can be calculated from this. However, the ground resistance value R calculated by the above method includes not only the ground resistance of the ground electrode E, but also the ground resistance of the ground electrode C, so it needs to be at the ground level of the EC A third ground electrode is established between EP and the value of the ground resistance RE of the ground electrode E can be calculated from the voltage Vp and the current I between EP. *The ground electrode P also has a resistance area, but the AC constant current impedance of the power supply is relatively high , Has no effect on detection.

Ground rod configuration method:

3-electrode method:

The distance between E (grounding wire) and auxiliary grounding rods P and C should be about 5-10M, and should be in a straight line. When there are obstacles that cannot be set in a straight line, a suitable angle can be used between EP and EC, generally Within 30 degrees.

2-electrode method:

It is already known that the grounding resistance point E (grounding wire) is nearby, it can be used to detect the unknown grounding resistance. The E terminal and E point of the grounding resistance meter are connected with a wire, and the P and C terminals are used as 1 terminal. The resistance value can be detected between;

The displayed value contains the resistance value of point E. The true effective value should be calculated. The grounding resistance value of point E must be subtracted;

Sand, sand grains, frozen soil, need to expose the soil surface;

Concrete requires the use of auxiliary nets. The auxiliary nets should be fully sprinkled with water to make it contact the earth as much as possible for accurate detection;

Asphalt, cannot be detected;

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