3P Earth Measurement - Chauvin Arnoux C.A 6456 Notice De Fonctionnement

4.2 2P AND 3P EARTH MEASUREMENT
4.2.1 DESCRIPTION OF THE FUNCTION
3P and 2P earth measurements are made in a power-off condition.
The measurements are made with two auxiliary rods (3 poles) and one auxiliary rod (2 poles), respectively.
Note however that measurements with 2 auxiliary rods are more accurate.
Measurement in 3P mode: the instrument generates an alternating current square wave (128Hz) between
terminals H and E, then measures the voltage between terminals S and E: from this voltage and the current
generated, it deduces global earthing resistance R
Measurement in 2P mode: the instrument generates a signal between terminals H and E, measures the
voltage on terminal H, and deduces resistance R
4.2.2 PREPARATION FOR THE MEASUREMENT (CONNECTION)
=> In SET-UP, set the value of the no-load voltage generated by the instrument: U
in a damp environment (see § 3.2).
=> If necessary,
adjust the alarm, R
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activate the alarm by pressing the ALARM key and 2nd key after SET-UP exit .
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An overshoot of an alarm threshold during a measurement is indicated by a continuous
audible signal
compensate the measuring cables (see § 3.3).
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E
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E
, in the SET-UP mode,
E ALARM
2 nd
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direction of alarm (> ou<)
location of decimal point
setting of the values of each of the 4 digits,
selected by successive presses on the
keys
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x3
59
= 50 V, or 25V
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