TENTECH MTD 20KWe Manual De Uso página 16

the distance between those points is enough for its corresponding
"influence areas" not to be overlapped. An "influence area" is the area
close to each electrode where a significant potential gradient is observed.
Out of that area, the potential is constant (potential plateau between
points A and B - Fig 05).
In order to obtain a valid measurement of the GDS resistances, it is
necessary to move the auxiliary current rod away enough to comply with
the "no overlap condition" of the areas of influence, and the voltage rod
(probe) must be set up in the potential plateau area. The criteria
commonly accepted is to consider that the radius of each influence area
is three to five times bigger than the electrode dimension.
The appropriate compliance of this condition must be checked by carrying
out three successive measurements of GDS resistances, keeping the
current rod position but moving the voltage rod about 2 meters between
measurements (points L, M, y N). If the three measurements show the
same result (within the earth meter specified error) the measurement
should be considered correct. Otherwise, the distance to the current rod
should be significantly increased and the process, repeated.
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