Iso-Tech IMT-3300 Manuel D'instructions page 15

5.3.4.1 Preparation
a) Ensure the pre-use checks at Para 5.1 above have been
carried out.
b) Slide the test-lead connector cover to expose the IEC test
socket.
c) Connect the mains lead (See Fig. 10) to the IEC socket of
the instrument.
d) Set the function switch to the "RCD x1/2" position.
e) Set the rated tripping current switch to the trip current
rating of the RCD to be tested.
f) Set the Loop/RCD phase angle selector switch to the 0° position.
g) Press the test button momentarily and release it. Check "V",
"0° " and "Lo" appear on the display.
h) Plug the moulded plug of the mains lead into the socket of
the circuit to be tested.
Note:
If testing of an RCD is to be carried out at a distribution board,
connect the distribution board test leads (see Fig. 11) in place
of the mains lead. Replace the red and black test probes with
crocodile clips if required. Connect the green crocodile clip to
the earth connection; the black neutral lead to the neutral and
the red phase test lead to phase. Disconnect the test leads in
the reverse order of connection.
5.3.4.2 Wiring check
 Caution! After connection, ensure the LEDs are as shown below:
P-E red LED is lit
P-N red LED is lit
Red LED is not lit
If the above sequence is not correct, do not continue the test as the
wiring is incorrect. Investigate and rectify the cause before continuing.
5.3.4.3 RCD test procedure
a) Press the test button and release it. Half the rated trip current will
be applied to the RCD for 2 seconds. The RCD should not trip.
b) Set the Loop/RCD phase angle selector switch to the 180° position.
c) Press the test button again and release it. Half the rated
trip current will again be applied to the RCD for 2 seconds.
Again, the RCD should not trip.
Note:If the RCD trips, the trip time will be shown on the display
and it is likely the RCD is faulty. Carry out further investigations
to verify the cause before replacing the RCD.
d) Set the function switch to the "RCD x1" position.
e) Set the rated tripping current switch to the trip current
rating of the RCD to be tested.
f) Set the Loop/RCD phase angle selector switch to the 0°
position.
g) Press the test button and release it. The rated trip current will
be applied to the RCD for 2 seconds and the RCD should trip.
The trip time will be shown on the display. Note the reading.
h) Reset the RCD.
i) Set the Loop/RCD phase angle selector switch to the 180° position.
j) Press the test button again and release it. The rated trip current
will be applied to the RCD for 2 seconds and the RCD should
trip. The trip time will be shown on the display. Note the reading.
For 30mA (typically) trip current RCDs which are used to provide
protection against electric shock, carry out a fast trip test as follows:
k) Set the rated trip current switch to the "150 Fast" position.
l) Set the function switch to the "RCD x1" position.
m) Set the Loop/RCD phase angle selector switch to the 0° position.
n) Press the test button and release it. 150mA will be applied
to the RCD for 2 seconds and the RCD should trip. The trip
time will be shown on the display. Note the reading.
o) Reset the RCD.
p) Set the Loop/RCD phase angle selector switch to the 180° position.
q) Press the test button again and release it. The rated trip
current will be applied to the RCD for 2 seconds and the
RCD should trip. The trip time will be shown on the display.
Note the reading.
Ensure the trip times noted in g), j), n) and q) comply with the
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