49
15.5 ICont – Contact current
Explanation
The contact current must be measured on every accessible
conductive part without protective conductor connection.
This is to ensure that there is no risk of a dangerous electric flow
via accessible conductive parts.
Accessible conductive SELV / PELV sockets can be scanned
optionally, as long as no damage to the test sample is to be
expected.
For this purpose, the following measuring methods may be used:
direct current measuring method
(preferred method for contact current)
differential current measuring method
alternative leakage current measuring method
The test sample must be disconnected from the mains.
For the direct and differential current measuring
method, the test socket is supplied with mains voltage.
The alternative leakage current measuring method is
only admissible if there are no mains voltage-
dependent switching devices in the device to be tested
and an RInsu measurement with a positive result has
been carried out before.
The measurement of the contact current may be
omitted for SELV / PELV conducting parts and for
information technology devices, if damage can be
caused to the test sample due to the necessary
adaptation (e.g. at interfaces) or due to the measuring
process.
If touchable conductive parts of different potential are
arranged in such a way that they can be touched
together with one hand, the sum of their contact
currents is to be regarded as the measured value.
For direct and differential current measurement, the
contact current must be measured with both polarities.
L<->N, N<->L
For the alternative leakage current measurement, L and
N conductors are shorted. The leakage current can be
twice the value for test samples with bipolar circuit
breakers.
For such test samples, the contact current may be
halved.
Check whether the measuring circuit is closed before
starting the test. Otherwise, no contact current is
measured and the test result will be incorrectly
displayed as being positive.
Test samples with capacitor circuits can cause higher
leakage currents. In individual cases, it must be
checked whether the measured leakage current values
comply with the applicable limits.
Class I, ICont, direct current measuring method
Place the test sample onto an insulated surface.
Connection diagram
VDE 0701-0702, VDE 0544-4
Circuit diagram
VDE 0701-0702, VDE 0544-4
Insert the shock-proof plug of the test sample into the test socket
of the appliance tester.
The test sample is supplied with mains voltage and must be
tested in all switch positions (device functions).
Use the test probe to scan all accessible conductive parts of the
test sample that are not connected to the protective conductor.
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