38
GMC-I Messtechnik GmbH
14
Measuring Low-Value Resistance of up to
100 Ohm (protective conductors and protective
equipotential bonding conductors)
According to the regulations, the measurement of low-value
resistance at protective conductors, earth conductors or bonding
conductors must be performed with (automatic) polarity reversal
of the test voltage, or with current flow in one (+ pole to PE) and
then the other direction (– pole an PE).
Attention!
!
Low-value resistance can only be measured at voltage-
free objects.
Select the Measuring Function
Connection
Via 2-pole adapter only!
Set Parameters
q
R
OFFSET
ON
/
OFF
– Compensation for Extension Cables with up to 10
If extension cables are used, their resistance can be deducted
automatically from the measurement results. Proceed as follows:
Ð
Switch
R
OFFSET
from OFF to ON. “
R
OFFSET
= 0.00
” appears in
the footer.
Ð
Select a polarity or automatic polarity reversal.
Ð
Short-circuit the end of the measurement extension cable with
the second test probe at the instrument.
Ð
Start measurement of offset resistance with I
N
.
Note
If the difference between RLO+ and RLO– is greater than
10% during automatic polarity reversal, no offset value is
accepted. In all other cases, the lower value is saved as
offset value.
Maximum offset value is 9.99
. Offset may result in neg-
ative resistance values.
Measuring R
OFFSET
The
R
OFFSET
x.xx
message now appears in the footer at the dis-
play, where x.xx is a value between 0.00 and 9.99
.
This value is subtracted from the actual measuring results for all
subsequent R
LO
measurements, if the
R
OFFSET
ON/OFF
key has
been set to
ON
.
R
OFFSET
must be newly ascertained in the following cases:
• during changeover between polarity types
• after switching from ON to OFF and back again.
Note
Only use this function when performing measurements
with extension cables.
When different extension cables are used, the above
described procedure must always be repeated.
q
Type / Polarity
The direction in which current flows can be selected here.
q
Limits – Setting the Limit Value
The limit value for resistance can be set as desired. If measured
values which exceed this limit occur, the red U
L
/R
L
LED lights up.
Limit values can be selected within a range of 1.0
to 20
. The
limit value is displayed above the measured value.
R
LO
ROFFSET: ON
OFF
Polarity
: +/- to PE
Limit value
:
R
LO
> Limit value
U
L
R
L
