Fluke 1625 - Compensation of Earth Electrode Connecting Lead

1625
Users Manual
44
Example:
Your clip-on transformer has a transformation ratio of tr = 1000:1. The meas-
urement without clip-on transformer results in a value R
E
= 0.983 Ω . With a
clip-on transformer a value of R
E
= 1.175 Ω is measured.
The deviation thus reads (1.175 - 0.983) Ω= + 0.192 Ω and referring to R
E
=
0.983 Ω an error evolves as following:
%5.19
983.0
192.0
%100 +=
Ω
Ω
×
The new transformation ratio to be set calculates:
1195
983.0
175.1
1000 =×=trnew
Compensation of Earth Electrode Connecting Lead
If the line resistance to the earth electrode can not be ignored, a compensation
of the connecting lead resistance to the earth electrode is possible. Proceed as
described below:
Measuring process:
R
RA
R
Earth/Ground Resistance 300k
AC
Resistance
300 k
DC Low Resistance 3k
CHANGE
ITEM
SELECT
START
TEST
DISPLAY
MENU
H/C2
S/P2
ES/P1
E/C1
4 POLE
3 POLE
4 POLE
2 POLE
2 POLE
4 POLE
OFF
3 POLE
EARTH / GROUND TESTER
1625
Auxiliary
earth
electrode
Earth
electrode
edw019.eps
Figure 15. Compensation of Earth Electrode Connecting Lead
1. Turn central rotary switch to position "R
E
3pole".
2. Wire instrument according to picture.