39
Measuring method
Differential current measurement
The connections on the mains side of the device are checked by
a differential current transformer. If there is a current difference
between the L and N conductors, a leakage or fault current is
proven to flow.
Please note:
If leakage/fault currents flow through different fault points, they
cannot be detected individually. In this case, the sum of all
leakage/fault currents is measured.
Direct current measurement
(place test sample onto
an insulated surface)
The leakage current is measured directly via a measuring resistor
(shunt).
Please note:
For test samples that are not placed onto an insulated surface,
leakage currents can flow off via parallel earth connections. This
reduces the measured leakage current and results in incorrect
measuring results.
Alternative leakage current measurement
The measuring circuit for the alternative leakage current
measurement is galvanically isolated from the mains and the L
and N conductors are bridged.
Please note:
By default, the potential-free testing voltage is
230 V AC
. In case
of a different testing voltage, the measured leakage current is
converted to correspond to a test result with mains voltage. The
measuring method may only be used if there are no mains
voltage-dependent electrically operated switching devices in the
test sample and after the insulation test has been passed.
Measuring accessories/ optional measuring
methods
Clamp measurement
The measurement is carried out using a
BENNING CM 9
leakage
current clamp.
Please note:
The leakage current clamp does not require a connection to the
ST 755/ ST 760
. The measured leakage or fault current is
entered manually in an input window of the appliance tester.
The leakage current clamp supports direct and differential current
measurement and can also be used for three-phase loads. (See
chapter 16.2.)
The test procedures 12 and 13 included in the appliance tester
represent automatic test procedures for using the
BENNING CM 9
leakage current clamp.
Three-phase measurement
(allows active measurements (with mains voltage))
The measurement is carried out using a
BENNING MA 2-16
measuring adapter.
When commissioning the
BENNING MA 2-16
, please observe
the operating manual supplied with it as well as all instructions for
the corresponding individual test.
The following individual tests can be carried out with the
BENNING MA 2-16
(see chapter 16.1):
continuity test of the protective conductor system
insulation test
measurement of the protective conductor current and contact
current using the following methods:
differential current measurement
direct current measurement
alternative leakage current measurement
functional test
The test procedures 17 and 18 included in the appliance tester
represent automatic test procedures for using the
BENNING MA 2-16
.
CEE line adapter
(allows only passive measurements (without mains voltage))
The measurement is carried out using a
BENNING MA 3
measuring adapter.
When commissioning the
BENNING MA 3
, please observe the
operating manual supplied with it as well as all instructions for the
corresponding individual test.
The following individual tests can be carried out with the
BENNING MA 3
:
protective conductor resistance (
RPE
)
insulating resistance (
RInsu
)
functional test and phase sequence test of cables
alternative leakage current:
o
e. g.
IPE
(protective conductor current),
ICont
(contact current),
ILeak
(device leakage
current),
IPLeak
(patient leakage current)
The test procedures 12, 13, 21 and 22 included in the appliance
tester represent automatic test procedures for using the
BENNING MA 3
.
