Measurement Of Earthing Resistances - Fluke 1625 User Manual

1625
Users Manual
1625 EARTH / GROUND TESTER
START
TEST
DISPLAY
MENU
AC
Resistance
Earth/Ground Resistance 300 k 300 k
RA R
2
POLE
4 POLE
3 POLE
4
POLE
CHANGE
ITEM 3 POLE
OFF
SELECT
Figure 7. Measurement of Interference - Voltages and Frequencies

Measurement of Earthing Resistances

This instrument is equipped with a 3 pole as well as a 4 pole resistance meas-
urement which renders measurements of resistances of earthing systems possi-
ble, as well as measurements of the soil resistivity of geological strata. A spe-
cific description of the different applications is given further on in this manual.
As a special function, the instrument offers measurements with an external
current transformer, with which a measurement of single resistance branches in
interlinked networks (lightning protection and high voltage pylons with ca-
bling) can be performed without seperating parts of the system.
To ensure most feasible interference suppression during measurements, the
instrument is equipped with 4 measuring frequencies (94 Hz, 105 Hz,
111 Hz, 128 Hz), with automatic switch over if necessary (AFC - Automatic
Frequency Control). The corresponding measuring frequency used for a spe-
cific measurement can be called and displayed with "DISPLAY MENU" after
the measurement. Additionally, one of the four measuring frequencies can be
selected and permanently set in special cases. In that case, in order to stabilize
the display, an average measurement can be carried out for up to 1 minute by
keeping the "START TEST" button pressed.
To determine the earthing impedance (R
close to the mains frequency (55 Hz) is carried out. At the activation of R*
through user's code, this measuring frequency is activated automatically.
32
H /C2
S/P2
DC Low Resistance 3k
R
2
POLE
4
POLE
ES/P1
E /C1
Earth
electrode
>20 m
*
) a measurement with a frequency
Auxiliary
earth
electrode
Probe
>20 m
edw010.eps