Fluke 1625 User Manual

1625
Users Manual
36
Measurement of Single Earth Electrode Resistances in
Mesh Operated Earthing Systems Using Selective
Clamp Method
This measuring method has been created to measure single earth electrodes in
permanently wired or mesh operated systems (e.g. lightning protection system
with several electrodes or high voltage pylons with earth cabling etc.). By
measuring the actual current flow through the earth electrode, this special
measuring method provides the unique possibility to measure selectively only
this particular resistance by means of a clip-on transformer (accessory). Other
parallel resistances applied are not taken into account and do not distort the
measuring result.
A disconnection of the earth electrode before the measurement is therefore no
longer necessary.
G
I
I
Z
tr
V
A
Aux. Earth
Electrode
Probe
I
3
U
meas.
RE
1
RE
2
RE
3
RS
RH
RE
3
=
U
meas.
I
3
=
U
meas.
tr
.
I
Z
edw014.eps
Figure 11. Measurement of Single Earth Electrode Resistances in Mesh
Operated Earthing Systems

Fluke 1625 Specifications

General

Storage Temperature	-20 °C to 60 °C
Testing Methods	3-pole fall-of-potential, 4-pole
Measurement Frequency	128 Hz
Power Supply	6 x 1.5 V AA batteries or optional AC adapter
Safety Rating	CAT II 300 V
Safety Standards	IEC 61010-1