Measurement Of Coupling - Chauvin Arnoux C.A 6460 Notice De Fonctionnement

3. Connect the rods to their respective terminals on the
instrument, using the leads.
4. Press the

button until the measurement is displayed.
Make sure that none of the three indicators is flashing,
otherwise check the setup (see § 3.5 Fault signalling) and
start measuring again.
5. Make a note of the measured resistance R.
6. The ground resistivity at point O is obtained by calculation:
ρ = 2π x R x a (with ρ in Ωm, R in Ω and a in metres)
3.4

Measurement of coupling

This measurement can be made to determine the coupling
resistance between two earth points. For instance, between
the neutral earth point and the ground earth point (EDF
distribution).
ground earth
point
Cut off the installation power supply and disconnect
the earth points.
1. Open the terminal bar between the E and ES terminals.
2. Using separate leads, connect the E and ES terminals to
the ground earth point and the H and S terminals to the
neutral earth point.
3. Press the

button until the measurement is displayed.
Make sure that none of the three indicators is flashing,
otherwise check the setup (see § 3.5 Fault signalling) and
start measuring again.
4. Note the R
value displayed.
mn
5. By also measuring Rm (ground earth resistance) and Rn
(neutral earth resistance) using the 62% method described
in § 3.2, the coupling coefficient can be calculated:
Rc
k = Rc
hence
Rm
neutral earth
point
_
Rm + Rn + Rmn
=
2
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