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Earth/Ground Tester
Procedure of Measurements
35
An accuracy test of the results is made with another measurement following
repositioning of the auxiliary earth electrode or probe. If the value stays the
same, the distance is sufficient. If the measured value changes, probe or auxil-
iary earth electrode must be repositioned until the measured value R
E
stays
constant.
Spike wires should not run too close to each other.
3-pole measurement with longer earth electrode connecting leads
Use one of the accessory cable drums as earth electrode connecting lead. Spool
off cable completely and compensate line resistance as described in “Compen-
sation of Earth Electrode Connecting Lead”.
Time average measurement:
If there is a warning "measured value unstable" (see “Procedures of Measure-
ment”, “Description of display”) after a test sequence, most likely it is caused
by strong interference signals (e.g. unsteady noise voltage).Nevertheless, to get
reliable values, the instrument offers the possibility of averanging over a
longer period.
1. Select a fixed frequency (see “Control loop” in “Operation”)
2. Keep the "START TEST" button pressed until the warning "measured
value unstable" disappears. Max. averaging time is approx. 1 min.
Evaluation of measured value:
Figure 10 shows the maximum permissible value of the Earth resistance which
will not exceed a permissible limit value, taking into account the maximum
usage error.
0
5
10
10
20
20
50
50
100
100
200
200
500
500
1000
1000
2000
2999
30003152
Desired Values
Measured Values
edw013.eps
Figure 10. Earth Resistance - Maximum Permissible Value