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9.5
Making a measurements – Three terminal resistance measurement using ART
.1 Connect the instrument as BELOW. Position the ICLAMP below the point where the Green Lead is attached to the Earth
Conductor. In practice the ICLAMP can be positioned directly on the Electrode under test, at a point below where the green Lead
is attached to the the Earth conductor.
I
CAT IV
300V
12-15V
1.2A
Electrode
under test
Potential
stake
Current
stake
.2 Set the rotary selector switch to the
3P
position.
.3 Press and release the
TEST
button [by holding the
TEST
button, the resistance measurement will be continually updated].
The instrument will perform pre-measurement checks, the status of which will be indicated on the display.
The three-terminal resistance reading using ART will be displayed
Under certain circumstances, the instrument may display a noise warning. This means that interference has been detected which
may impair the accuracy of the measurement. In particular, the reading could be lower than the actual resistance. The resistance
of the electrode or system must be verified by an alternative method.
Note:
■
The instrument will display the warning triangle and an excessive noise voltage indicator if the ground noise voltage is
above 20 V pk-pk (7 Vrms).
■
The instrument will display the warning triangle above 2 A – no ART testing is possible under this condition.
■
The instrument will display the warning triangle and an over-range condition above 20 A – no ART testing is possible
under this condition.
■
Ensure that the ICLAMP jaw mating surfaces are free of dust and contamination and that they contact completely when
the ICLAMP is closed.
■
Currents carried by conductors in close proximity to the ICLAMP may affect calibration and reduce the accuracy of
measurements made.
■
Re/Rs ratio must be less than 100, where Re = Earth resistance, Rs = Shunt resistance
