HT instruments HT7051 - Manual (Page 24)

HT2055
EN - 23
7.4 GROUND RESISTIVITY MEASUREMENT
For the ground resistivity measurement the test current is injected through two current
probes (C1/H and C2/E). The voltage probes S and ES must be placed between the
current probes (equidistance ‘a’ between probes must be considered). Using different
distances between the test probes means that the material is measured at different
depths. By increasing the distance ‘a’ a deeper layer of ground material is measured (see
Fig. 27)
Fig. 27: Connection of the unit for ground resistance measurement
1 Use or keys and select the EARTH RE measurement on the station unit
2 Use the  or  keys to select the “EARTH ” measurement. The below screen is
displayed:
Fig. 28: Main screen of ground resistance measurement
3 Use
the  or  keys to select the “a” parameter. Use the  or  keys to set the value
expressed in meters into the range 0.1 ÷ 30.0 by steps of 0.1m
4 Fit the auxiliary test probes at the same distance “a” set on the station unit and connect
the input terminals C1/H, C2/E (current probes), ES and S (voltage probes) to the earth
system under test by using the cables supplied as accessories (see Fig. 27)
5 Press
TEST
key to perform the measurement. The result is displayed
Fig. 29: Result screen of ground resistance measurement
Where:
  Measured value of ground resistivity
Rp  Voltage probe resistance (sum of S+ES)
Rc  Current probe resistance (sum of C1/H +C2/E)