Fluke 1625-2 User Manual page 33

Press "START TEST" button.
Now a fully automated test sequence of all relevant parameters like auxiliary earth
electrode and probe and earth electrode resistance is implemented and finished with the
display of the result R
1. Read out measured value R
2. Call R and R
S
Remarks for the Setting of Earth Spikes
Before setting the earth spikes for probe and auxiliary earth electrode make sure that the
probe is set outside the potential gradient of earth electrode and auxiliary earth electrode.
Such a condition is normally reached by allowing a distance of >20 m between the earth
electrode and the earth spikes as well as to the earth spikes to each other. An accuracy
test of the results is made by 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 auxiliary earth electrode must be repositioned
until the measured value RE stays constant.
Spikes wires should not run too close.
3-pole Measurement with Longer Earth Electrode Connecting Leads
1. Use one of the accessory cable drums as earth electrode connecting lead.
2. Spool off cable completely and compensate line resistance as described in
"Compensation of Earth Electrode Connecting Lead".
Time Average Measurement
If there is a warning "MEASURED VALUE UNSTABLE" (see Table 5) after a test
sequence, most likely it is caused by strong interference signals (for example, unsteady
noise voltage). To get reliable values, the instrument offers the possibility of averaging
over a longer period.
1. Select a fixed frequency (see Control Loop).
2. Keep the "START TEST" button pressed until the warning "MEASURED VALUE
UNSTABLE" disappears. Maximum averaging time is approximately 1 minute.
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E
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E
with "DISPLAY MENU".
H
Earth/Ground Tester
Advanced Operation
25