-1
6
-
measured earthing object and that of commercial earthing object, that is:
R=RX
＋
re
In which:
R
is the tester reading value;
RX
is the earth ground resistance value of measured earthing
object;
re
is the earth ground resistance value of common earthing object
like commercial use power system.
Then, the earth ground resistance value of measured earthing
object is:
RX=R
－
re
8
．
Soil Resistivity Measurement
Soil resistivity
ρ
is a determining factor of earthing resistance of
earthing body.
In different types of
soil, there is a different soil
resistivity. Even the same kind of soil, due to different temperature
s
and water content and so on, the soil resistivity will correspondingly
show
a significant change.
Soil resistivity is measured by 4-pole method (
ex:
Wenner method)
According to formula
ρ=2πaR(Ωm)
calculating soil resistivity
ρ
, its
unit is
Ωm
, in which:
a
——
probe separation
distance
R
——soil resistivity between electrode
P
(S)-
ES
4-pole method (Wenner method): Connect testing wires as shown
below, pay attention to the distance between auxiliary earthing
probes
,
and the embedding depth. Respectively insert
C
(H)
,
P
(S)
,
ES
,
E
auxiliary earthing rods deep into the earth in a straight line, and then
connect testing wires (red, yellow, green, black) corresponding to
C(H)
,
P(S)
,
ES
,
E
of interfaces and measured auxiliary earthing
probe
.
After completing
wire connection
s
, rotate
FUNCTION
rotary switch to “
ρ
EARTH
”,
long press “
SET
” button (about 3 seconds) to enter setting,
quickly
