Earth/Ground Tester
Advanced Operation
23
4. Read out measured value R
E
.
Note
Before setting the earth stakes 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
stakes as well as to the earth stakes to each other. An accuracy test of the
results is made with another measurement after repositioning of auxiliary
earth electrode or probe. If the result is the same, the distance is sufficient.
If the measured value changes, probe or auxiliary earth electrode must be
repositioned until the measured value R
E
remains constant.
Stake wires should not run too close.
5. Apply current transformer to next pylon stub.
6. Repeat measuring sequence.
Current feeding point of measuring current (alligator clip) and the polarity of the split
core current transformer has to be left unchanged.
After values of R
Ei
of all pylon foots are determined, the actual earth resistance R
E
has to be calculated:
4321
1111
1
EEEE
E
RRRR
R
+++
=
Note
If the displayed R
E
value is negative despite correct orientation of the
current transformer, a part of the measuring current is flowing upwards into
the tower body. The earthing resistance, thus coming into effect, correctly
calculates if the individual equivalent resistances (under observation of their
polarity) are inserted into the equation above.
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Weight and Dimensions
