User Manual

10 GMC-I Messtechnik GmbH
4.1.2 Automatic Recognition of Mains Connection Errors
The device automatically recognizes mains connection errors if
the conditions in the following table have been fulfilled. The user is
informed of the type of error, and all measuring functions are dis-
abled in the event of danger.
Type of Mains
Connection Error
Message Condition Measurements
Voltage at protective con-
ductor PE
to finger contact
(START/S
TOP key)
Display at the
instrum
ent
Press START/STOP
butt
on
U 25 V
PE key:
< 1 M
2
All measurements
disabled
Protective conductor PE
and p
hase
conductor L
reversed and/or
neutral conductor N
interrupted
Voltage at PE
> 100 V
Impossible
(no s
upply power)
Line voltage
< 180 V / < 90 V
(
depending on mains)
U
L-N
< 180 V
U
L-N
< 90 V
Conditionally
p
ossible
1
Test for IT/TN system
Display at the
instrum
ent
Connection
N PE
> 50 k
Possible under
ce
rtain circum-
stances
1
10 A/25 A R
PE
measurements are only possible with line voltages of
115/230 V and line frequencies of 50/60 Hz.
2
If the user of the test instrument is too well insulated, the following error mes-
sage may appear: “Interference voltage at mains connection PE”
Note
Finger Contact 
During this test for correct mains connection, a voltage
mea
surement is performed between the finger contact
and PE at the test instrument’s mains connection, and its
reference potential is acquired via the user’s body resis-
tance to the conductive start key. In order to obtain reli-
able measurement results, this r
esistance value must be
less than 1 M.
If the user is wearing insulating shoes or
gloves, or is standing on an insulating floor covering,
erroneous measurements and display of the “Interference
voltage at mains connection PE” message may result. Try
to reduce resistance in this case, for example by touching
ground potential with the other hand (e.g. a radiator, but
not an insulating wall etc.).
Attention!
!
If, while testing protective conductor potential, you deter-
mine that the main
s protective conductor is conducting volt-
age (i
n accordance with the first two cases mentioned),
no further measurements may be performed with the test in-
strument. If this is the case, potentially dangerous voltage
is also present at the accessible earthing contacts of the
standard socket (test socket). Immediately disconnect
the test instrument from the mains and arrange to have
the fault eliminated at the mains connection.
Note
Voltage at the electrical system’s protective conductor PE may
result in distorted measurement values during testing for
the absence of voltage, or during leakage voltage mea-
surements.
4.2 Connecting Test Probe P1 or P2
Insert the double plug from test probe P1 or P2 into socket 1 or 2
respectively such that the plug with the white ring makes contact
with the socket with the vertical bar.
The white ring identifies the terminal f
or the high current conduc-
tor which is safeguarded by the neighboring fuse link.
Note
Difficultly in contacting exposed conductive parts when using
the standard probe with test tip

In order to assure good contact, surface coatings must
be removed from devices under test with special tools at
a suitable location. 
The tip of test probe P1 is not suitable for scratching away
paint, because this may impair its coating and/or mechani-
cal strength. Brush probe Z745G may be more suitable than
the test probe in certain individual cases.