Operation Manual

GMC-I Messtechnik GmbH 15
R
PE
Protective Conductor Resistance
Measuring and Storing an Offset Value when Using a 2
nd
Probe
When a second probe is used which is connected to sockets 3
and 4, 4-wire measurements are not provided for. However, the
ohmic resistance of the cable for the second probe can be auto-
matically deducted from the measuring result by determining an
offset value. Please proceed as follows to this end:
Ð Connect the two probes to sockets 1 and 2 or 3 and 4,
respectively. The probe extension cable or the probe
cable drum must generally be connected with sockets 1
and 2. Contact both probes with the same reference point.
This is equivalent to short-circuiting the two probes. The offset
value established in this way is retained by pressing the key on
the right (only for values < 2 Ω), displayed briefly and will be
deducted from all future measuring results. You can store this
offset value, see key below.
Ð After measuring the offset value, the latter can be per-
manently stored with the key on the right so that it is
available after switching the instrument on again.
Ð Press the key on the right for loading a stored offset
value.
Note
Only use this function if you work with extension cables.
When using different extension cables, the procedure
described above must principally be repeated.
Sequence
Ð Select the test: ↑↓ keys.
Ð Connect the DUT to the test socket and connect the probe.
Ð Start the test: Press the STARTSTOP key.
Ð
1 probe:
Contact one of the conductive parts of the housing which is con-
nected to the protective conductor with the probe (socket 1–2).
Ð
2 probes:
A cable drum or extension cable (socket 1–2) is contacted
with the reference point (e.g. overall earth electrode of a unit), the sec-
ond probe (socket 3-4) is contacted with the test point.
During measurement, the
connector cable
must only be moved to the ex-
tent that it is accessible during repair, modification or testing. If a change
in resistance occurs during the manual test step of the continuity test, it
must be assumed that the protective conductor is damaged, or that one
of the connector contacts is no longer in flawless condition.
Ð Measured values are displayed.
Ð End the test: Press the STARTSTOP key.
Ð Read the measured value and compare it with the table of
permissible limit values.
Examples of Maximum Permissible Limit Values for Protective Conductor
Resistance for Connector Cables with Lengths of up to 5 m
Test
Standard
Test curren t
Open-
Circuit
Voltage
R
PE
Housing –
Device Plug
R
PE
Housing –
Mains Plug
Connector
Cable
IEC 60601
IEC 61010
Production
Not defined 0.1 Ω 0.1 Ω 0.1 Ω
IEC 62353
(VDE 0751-1)
> 200 mA
4 V < U
L
<
24 V
0.2 Ω 0.3 Ω 0.1 Ω
VDE 0701-
0702
—0.3Ω
+ 0.1 Ω
for each addi-
tional 7.5 m