Chauvin Arnoux C.A 6116, User Manual

Page: 26 / 96

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3.6. MEAsUREMEnt of tHE lInE IMPEDAnCE (Z
i
)
The loop impedance measurement Zi (L-N, L1-L2, or L2-L3 or L1-L3) is used to calculate the short-circuit current and size the protec-
tions of the installation (fuse or RCD), whatever type of neutral the installation uses.
3.6.1. 3.6.1. DEsCRIPtIon of tHE MEAsUREMEnt PRInCIPlE
The device generates pulses having a duration of 300 µs and an amplitude of at most 5 A between the L and N terminals. It then
measures the voltages U
L
and U
N
and from them deduces Z
i
.
The device then calculates the short-circuit current Ik = U
LN
/Z
i
the value of which serves to check the proper sizing of the protec-
tions of the installation.
3.6.2. 3.6.2. MAkInG A MEAsUREMEnt
Set the switch to Z
i
.
At the time of connection, the device first checks that the voltages present
on its terminals are correct, then determines the position of the phase (L) and
of the neutral (N) with respect to the protective conductor (PE) and displays
it. If necessary, it then automatically switches the L and N terminals so that
the line impedance measurement can be made without modifying the con-
nections of the terminals of the device.
SET UP
OFF
L
PE
N
Rb
R
E
R
N
R
L
L
PE
N
Rb
R
N
R
L
Ra
Case of a TT installation Case of a TN installation
Case of an IT installation
L
PE
N
R
N
R
L
Ra
Z
The alarm, if activated, serves to inform the user, by an audible signal, that the measurement is above threshold, making it un-
necessary to look at the display unit to check this point.
The signal can be smoothed to produce a mean of values. But the measurement then takes longer.
Connect the measuring cable to the device, then to the socket outlet of the instal-
lation to be tested.
If you use the measuring cable that is terminated by three leads, you can connect
the PE lead (green) to the N lead (blue). Otherwise, the device cannot display the
position of the phase. But this does not prevent making the measurement.