Amprobe GP-2 Geo-Test - Manual (Page 15)

GP-2 GeoTest
EN - 15
4.3. "
ρρ" MODE (Resistivity of the Earth)
The measurement is taken according to CEI 64.8, IEC 781, VDE 0413, EN61557-5
standards.
4.3.1. Selecting the units of measure
WARNING Whenever the units of measure are changed the
instrument will perform a hard reset and all the data in the
memory will be erased (see paragraph 6.1).
SELECT THE UNIT press and hold the "RCL" key and turn the rotary switch. The
instrument will display a screen that permits selection of the
correct measurement unit: m or ft (used to determine distance
between the ground rods) with the s or t keys. Press the
SAVE or ESC key to save the measurement unit selected.
NOTE! Regardless on the unit of distance D set up (either ft or m) the resistivity will
be automatically calculated in OhmMeters!
4.3.2. Operating Instructions
Measuring procedure:
F
Drive the 4 earth rods into the ground at the same distance D. The distance D
between the rods is usually 3 to 30 ft (1 to 10 m).
The distance D between the rods determines the depth at which the earth
resistivity is measured. In order to identify the distance (and therefore depth)
corresponding to the lowest resistivity value, the test must be repeated several
times, positioning the rods at different distances. This depth will then have to be
physically reached by the rods of the earth equipment.
F
Insert the 4 connectors (black, red, blue and green) of the cables into the
corresponding input terminals of the instrument (E, S, H, ES).
F
Connect the alligator clips as shown in Figure 4.
a
a
a
ES
H
E
CAT III
440 V P-N-PE
2 5 0 V
S H
Figure 4: 4 wire earth resistivity measurement