Manual

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Fig 9
6.5 Loop impedance at 3 phase equipment
In order to test the Loop impedance at 3 phase equipment the optional OMA
DIEC(Model7133) is necessary.
Use the same procedure as in 6.4 above ensuring that only one phase is
connected at a time i.e.：First Test: red prod to phase 1, black prod to neutral,
green crocodile clip to earth.
Second Test: red prod to phase 2, black prod to
neutral, green crocodile clip to earth etc.
WARNING：N EVER CONNECT THE INSTRUMENT TO TWO
PHASES AT THE SAME TIME.
Testing as described in 6.4 and 6.5 above will measure the Phase-Earth loop
impedance. If you wish to measure the Phase-Neutral loop impedance then the
same procedure should be followed except the earth clip should be connected
to the neutral of the system i.e.: the same point as the black neutral probe.
If the system has no neutral then you must connect the black neutral probe to
the earth i.e.: the same point as the green earth clip. This will only work if there
is no RCD in this type of system.