Earth/Ground Tester
Procedure of Measurements
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 RE 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.
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| Desired Values |
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| Measured Values |
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edw013.eps
Figure 10. Earth Resistance - Maximum Permissible Value
35
