Measuring Earthing/Grounding Resistance (R A ) - LEM SATURN 100 plus Instrucciones De Uso

Measuring

3.8 Measuring Earthing/Grounding Resistance (R A )

In this measuring mode, earthing/grounding resistances up to 10 kOhm can be
measured in three ranges. Measurements are effected by current-voltage
measurement with the help of a probe as a reference point. Any occurring noise
voltages up to 20 V between the probe and the PE wire can be measured and
displayed and will not falsify the result of measurement!
For voltages > 20 V, no measurement is performed, and the probe voltage is
displayed automatically. In this case the probe should be repositioned so that the
voltage falls below 20 V. Because of the measuring method chosen, even high
probe contact resistances up to 10 kOhm can be neglected and will not falsify the
result of measurement (automatic check of the probe resistance before
measurement).
If during measurement contact voltages > 50 V with respect to earth/ground occur,
measurement is automatically terminated within 200 ms.
For measurements in FI-protected systems, please use the measuring mode
„FI-Circuit Breaker Test With Probe, section 3.7. In this mode,
earthing/grounding resistance measurement is possible without tripping the
FI-circuit breakers.
Note: For very accurate measurements of small earthing/grounding resistances
below 1 Ohm, the measuring-lead zero compensation may be performed as per
section 3.10.
Basic Circuit Diagram
I
P
A
R
R
o
Earth connection
L1
L2
L3
U
R
P
I
V
R
R
E
reference
ground
probe
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