Earth/Ground Measurement (4-Pole) - AEMC 6470-b User Manual

If you find the same values, your measurement is reliable. If the measured values
are substantially different, it is likely that they were influenced by earth currents or
a groundwater source. It may be useful to drive the electrodes deeper and/or wet
the ground near them to reduce their contact resistance with the soil.
Avoid routing the connecting cables of the earth electrodes near or parallel to other
cables (transmission or supply), metallic conductors, rails, or fences: high test fre-
quencies may cause cross-talk and affect the measurements.

5.5 Earth/Ground Measurement (4-Pole)

This function is suited to the measurement of very low earth resistances. It
provides better resolution (10x better than 3P measurement) and there is no need
to compensate for the resistance of the measurement leads.
1.
Set the switch to
2. Place electrodes H (Z) and S (Y) at least 30m apart.
Ω
Ω
In order to avoid electromagnetic interference, it is best to unwind the full length of
each cable from the reel, to keep the cables as far apart as possible on the ground,
taking care not to form loops, and to avoid placing the cables near or parallel to
metallic conductors (cables, rails, fences, etc.). Connect the cables to terminals
H (Z) and S (Y); disconnect the earth strap from the rod under test, then connect
terminals E (X) and ES (Xv) to the earth electrode to be tested.
3. Start the measurement by pressing the START/STOP button.
32
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