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Ground resistance tester reading

time:2020/6/6   source:华天电力  reading:834 time

In the grounding resistance test, what are the reasons for the inaccurate reading of the grounding resistance tester? How to solve it?

1. Since the ground resistance tester measures the ground resistance of the grounding body through the transmission and reception of iron, the interference between the two irons and the distance between the two brazing and the grounding body will be too close, which will cause errors. Therefore, the grounding body, voltage pole, and current pole should be arranged in sequence during the measurement, and the three points should be in a straight line, with a distance of 20 meters from each other, to avoid this problem.

2. The depth of the iron brazing should be greater than 1/4 of the length of the iron brazing, otherwise, test errors will occur, so try to drill the iron brazing as deep as possible.

3. Due to poor insulation or short circuit of the equipment, the grounding device generates a certain ground voltage to the ground, which makes the reading unstable during the measurement. At this time, the power should be cut off for detection, or the place where the card is disconnected for detection to avoid ground The effect of voltage on detection.

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4. Poor contact is also one of the reasons for inaccurate readings. The measured object is rusty. During the inspection, you will find the phenomenon of on-off or on-time or large resistance. At this time, first remove the rust. If it cannot be eliminated, check the continuity of the detection line with the resistance of the ground resistance tester.

5. When testing high-rise buildings, the wires are too long and too thick to cause measurement errors due to the increase in line resistance and induced voltage. Conductors with lower line resistance should be used to minimize measurement errors.

6. When the testing environment has a cushion soil layer, the resistivity of the two layers of soil is different, which is easy to cause measurement errors, and the method of deep iron brazing should be used. Make it fully contact with the soil under the cushion or avoid the cushion soil to reduce the measurement error.

7. When the grounding devices and metal pipes and other metal objects buried in the test are more complex, it may change the current direction of each pole of the measuring instrument and cause poor measurement or instability. You should first understand the layout of the grounding body and the metal pipe and choose Measure where the impact is relatively small.

8. There is a potential difference or a strong magnetic field on the ground, which is easy to cause inaccurate measurement. Therefore, the measurement should be as far away as possible from a place with a large potential difference or a strong magnetic field. If it is unavoidable, the detection line should be relatively shortened to reduce the measurement error.

9. If the operation is not in accordance with the instructions, the grounding resistance tester is not repaired in time, the grounding resistance tester is inaccurate or has not been identified for a long time, and other factors will also cause measurement errors. Therefore, in the test, the grounding resistance tester is to operate according to the instructions The daily maintenance of the grounding resistance tester is also very important.

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