User Manual

48 GMC-I Messtechnik GmbH
12 Measuring Low-Value Resistance up to 200 Ohm
(protective conductor and equipotential bonding
conductor)
According to the regulations, the measurement of low-value resis-
tance at protective conductors, earth conductors or bonding con-
ductors 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 to PE).
Attention!
!
Low-value resistance must only be measured at voltage-
free objects.
Select Measuring Function
Connection
Via 2-pole adapter only!
Set Parameters
❑ ROFFSET ON/OFF
– Compensation for Extension Cables with up to 10 Ω
If measurement cables or extension cables are used, their resis-
tance can be deducted automatically from the measurement
results. Proceed as follows:
➭ Switch R
OFFSET from OFF to ON. “ROFFSET = 0.00 Ω” appears in
the footer.
➭ Select a polarity option or automatic polarity reversal.
➭ Short-circuit the end of the measurement extension cable with
the second test probe at the instrument.
➭ Start measurement of offset resistance with I
ΔN
.
An intermittent acoustic signal sounds first,
which is then accompanied by a blinking
warning to prevent an offset value which has
already been saved from being unintentionally
deleted.
➭
Start the offset measurement by press-
ing the release key again or abort mea-
surement by pressing the
key
?
ON/START
(here = ESC).
Note
If the offset measurement is stopped by an error pop-up
(Roffset > 10 Ω or difference between RLO+ and RLO–
greater than 10%), the offset value that has last been
measured is retained. Inadvertent deletion of an offset
value once established is thus almost ruled out! The
respectively smaller value is otherwise stored to memory
as an offset value. The maximum offset value is 10.0 Ω.
Negative resistances may result due to the offset value.
Measuring ROFFSET
The ROFFSET x.xx Ω message now appears in the footer at the dis-
play, where x.xx may take a value between 0.00 and 10.0 Ω. This
value is subtracted from the actual measuring results for all sub-
sequent R
LO
measurements, if the ROFFSET ON/OFF key has been
set to ON.
Roffset must be determined anew in the following cases:
• After switching to a different polarity option
• After switching from ON to OFF and back again
You can deliberately delete the offset value by switching ROFF-
SET from OFF to ON.
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.
❑ Type / Polarity
The direction in which current flows can be selected here.
❑ Limits – Setting the Limit Value
The limit value for resistance can be set as desired. If measure-
ment values which exceed this limit occur, the red U
L
/R
L
LED
lights up. Limit values can be selected between 0.10 Ω and
10.0 Ω (editable). The limit value is displayed above the measured
value.
R
LO
ROFFSET: ON ↔ OFF
Polarity: +/- to PE
Polarity: +/- to PE
with ramp function
Limit value:
R
LO
> Limit Value
U
L
⏐ R
L