Preparation - Iso-Tech IMT-3300 Manuel D'instructions

Fig 10
Fig 11
5.3.1 Loop impedance measurement at a mains socket outlet

5.3.1.1 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 above) to the IEC
socket of the instrument.
d) Set the function switch to the "20Ω Loop" range.
e) Press the test button momentarily and release it. Check "V"
and "Lo" appear on the display.
f) Plug the moulded plug of the mains lead into the socket of
the circuit to be tested.
5.3.1.2 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.
5.3.1.3 Loop test
a) Note the mains voltage as shown on the display.
b) Press and release the test button. The value of the loop
impedance will be shown on the display. If the display shows
'OL', the measured resistance is greater than the range
selected. Select the 2000Ω range and repeat the test.
Note:
Tests carried out with the function selector switch in the 2000 Ω
position pass a test current of 15mA which is less likely to trip an RCD.
If any in-circuit RCD trips, set the phase-angle selector switch to the
alternative position, reset the RCD and repeat the test. If the test
cannot be carried out without tripping the circuit RCD, temporarily
replace the RCD with a suitably rated MCB for the duration of the tests.
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