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Problems in the use of ground resistance tester

time:2020/9/19   source:华天电力  reading:239 time

When the ground resistance tester measures the grounding of high-rise buildings, why is the resistance value greater than the ground resistance. And it shows that the data jumps seriously. What caused it and how to avoid it?

 

Earth Resistance Tester.png


This is because there is a certain resistance between the ground lead of the high-rise building and the ground during the measurement of high-rise buildings (R ground wire). In addition, the test line connected from the measurement point on the high-rise building to the ground instrument exists in the air. Line inductance. (WL) So the measured resistance value of the ground point of the high-rise building is R=R ground wire+WL+R ground. Ground resistance R=R ground.

 

The measurement data jitter is more serious than the ground measurement. This is because the test line is lengthened in the air, like an antenna that leads some radio and electromagnetic clutter signals in the air to the instrument through the test line, which causes serious interference and makes the measurement data jitter. , The solution is to use a coaxial wire as the test lead, connect the coaxial wire and the core wire together, and connect it to the test point. Connect the shielded wire at the other end of the coaxial cable to the C2 end of the instrument (ie current pole), and connect the core wire of the coaxial cable to the P2 end of the instrument (ie voltage pole), which can better solve the measurement of high-level grounding The resistance is caused by interference due to the long lead.


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