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completed, the LCD displays the line resistance and stores the value. The
checked line resistance value is automatically deducted from this start-up
ground resistance measurement.
Shutdown does not save the calibration line resistance. The next time you
turn on the power, you need to verify again..
5
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Grounding Resistance Precision Measurement
When testing the grounding resistance, first confirm the grounding
voltage of the grounding wire, that is, the voltages of H and E or S and
FR must be less than 20V. If the grounding voltage is more than 5V, the
measured value of the grounding resistance may be inaccurate. At this
time, the measured grounding device should be powered off first, so that
the grounding voltage is reduced and then the grounding resistance test
is performed.
Four-wire test: The four-wire test eliminates the influence of the contact
resistance (usually dirt or rust) on the measured grounding body, auxiliary
grounding bar, test clip, and the input interface of the instrument to the
measurement, eliminating the effect of the wire resistance to the
measurement. It is better than the three-line test.
See the following figure: Beginning with the measured object, generally
spaced 5m ~ 20m, respectively, the S, H auxiliary grounding rod is buried
deep into the ground in a straight line, the ground test line (black, green,
yellow, red) from the instrument E, FR, S, and H interfaces are initially
connected to the ground electrode E under test, the auxiliary voltage electrode
S, and the auxiliary current electrode H.
The distance between the measured grounding body E and the current pole
H should be at least 5 times the buried ground depth (h) of the measured
grounding body, or 5 times the buried ground electrode length (d).
Measure the total grounding resistance of a complex grounding system. The
distance d is the distance of the largest diagonal of the grounding system.
During the test, the test leads cannot be intertwined with each other.
Otherwise, the test accuracy may be affected.
