Measurement Principle
Appx.
3
Appendix 2
Measurement Principle
While applying a voltage of AC power supply between H(C)
electrode and E electrode, the flowing AC current
I is measured with
an ammeter. In addition, the voltage
V
between S(P) electrode and
E electrode that is caused by the flow of the current
I is measured
by an AC voltmeter.
The earth resistance
R
X
of E electrode is derived from the measured
current
I and voltage V. It is not possible to accurately measure
the voltages between H(C) - E electrodes and between H(C) - S(P)
electrodes.
Voltmeter
AC Power
Supply
l
I
V
=
R
X
×
I
R
X
=
V/I
E Electrode
S(P) Electrode
H(C) Electrode
Ammeter
www.calcert.com
1.800.544.2843
0
5
10
15
20
25
30
