User Manual

28 GMC-I Messtechnik GmbH
8.6 Touch Current – IB
Application
Make sure that the contacted parts are not grounded.
Definition
Current which flows from housing parts which are not connected
to the protective conductor via an external conductive connection
to earth or another part of the housing. Flow of current via the
protective conductor is excluded in this case.
The following designations are also common:
housing leakage current, probe current
Direct Measuring Method:
DUT Mains Plug Connected to Test Socket
Test Probe P1 to P1 Terminals
Figure 1/4: The DUT is operated with line voltage. Current which
flows to the protective conductor via exposed conductive parts is
measured by means of the probe. The measurements must be
performed with mains plug polarity in both directions. Polarity is
reversed with the NL/LN key. The TRMS, the AC or the DC com-
ponent of the current is measured.
Note
regarding protection class I DUTs:
Parts may or may not be grounded.
Coincidental grounding only occurs in the event of an
error.
Differential Current Method:
DUT Mains Plug Connected to Test Socket,
Test Probe P1 to P1 Terminals
Figure 2/4: The DUT (PC2) is operated with line voltage. Differen-
tial current which flows via the two mains conductors is measured
(current clamp measurement concept). The measurements must
be performed with mains plug polarity in both directions. Polarity
is reversed with the NL/LN key. The current’s AC component is
measured. Accessible conductive parts must be contacted with
test probe P1.
Alternative Measuring Method (equivalent leakage current)
DUT Mains Plug Connected to Test Socket,
Test Probe P1 to P1 Terminals
Figure 3/4: After activating test voltage, leakage current is mea-
sured between short-circuited mains conductors L and N (DUT
mains plug) and accessible conductive parts (probe contact). The
TRMS, the AC or the DC component of the current is measured.
Direct Measuring Method for Permanently Installed DUTs
Figure 4/4: The DUT is operated with line voltage from a perma-
nent installation. Leakage current is measured between the pro-
tective conductor at the mains and the output sockets for safety
extra-low voltage at the DUT, one after the other, with the help of
the test probe. Furthermore, accessible, conductive parts which
are not connected to the housing must also be contacted.
Switch
Setting
Meas.
Variant
Measuring Function
Single measurements, rotary switch level: green
Measurements at DUTs with line voltage
I
C
Direct
Diff.
Alt.
I
T
Touch current, TRMS
I
T~
AC component
I
T=
DC component
U
LN
Test vo lta ge
I
B