GMC-I Messtechnik GmbH
9
4.4
Varistor Test (PRCD-K)
During this measurement, the voltage is
ascertained at which the varistor becomes
conductive, thus checking the varistor for
correct functioning as well. Measurement
can be performed by means of an ISO ramp,
or with a fixed test voltage of 50 V.
As a prerequisite for this measurement, the
device under test must be switched on.
➭
Connect the
PROFITEST MXTRA
test instru-
ment to the
PE IN
and
PE OUT
sockets via
the 2-pole measuring adapter.
➭
Perform the measurement as described
in the operating instructions for the
PROF-
ITEST MXTRA
(section 11).
➭
The evaluation of the measured varistor re-
sistance depends on the manufacturer’s
specifications (PRCD-K from Kopp: e.g. 12
to 22 V according to Kopp).
Note on Kopp Test Specification:
PRCD-K (Varistor in Protective Earth Circuit)
Test Sequence by Kopp:
1.) Connect operating voltage (e. g. 230 V/
50 Hz) and 24 V AC voltage source.
2.) Select resistance (R) depending on the
residual current of the PRCD-K:
For PRCD-K
with In = 30 mA
→
R = 220
Ω
/1 W.
For PRCD-K
with In = 10 mA
→
R = 620
Ω
/0.5 W.
3.) Switch on PRCD-K by pressing the ON
button.
4.) Press key <T>
→
device must trip
→
PE
circuit is functioning properly.
The shutdown test of the PRCD-K stipulated
by KOPP at this point is performed in con-
nection with the testing of the RCD protec-
tion device with a continuously rising resid-
ual current until the device is tripped.
5
Protective Conductor Current
Measurement
➭
Connect the PRCD as described in sec-
tion 3.3.
➭
Switch mains power on by turning the
right-hand
rotary selector switch to the
1~ ON
or
3~ ON
position depending on
the number of phases.
➭
Single-phase PRCD:
Turn the
left-hand
ro-
tary selector switch to the first
ON
posi-
tion in the orange area for single-phase
interruption.
➭
3-phase PRCD:
Turn the
left-hand
rotary se-
lector switch to the first
ON
position in the
green area for 3-phase interruption.
➭
Enclose the external protective conduc-
tor loop (5) with the jaws of the current
clamp transformer.
➭
Read the measured value for protective
conductor current at the current clamp
transformer.
Protective conductor current should not
exceed 3.5 mA.
Example of a Single-Phase PRCD
PROFI
TEST
⏐
P
RCD
Measurement with the PROFITEST MXTRA