Chauvin Arnoux C.A 6115N, User Manual

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Before and after method:
This method makes it possible to trip an RCD even if another RCD of lower rating comes before it. If this
is the case, connect the instrument to a phase before the RCD to be tested and connect the remaining
test leads (neutral and earth) to the neutral after the RCD to be tested. This method can only be used on
single-phase or three-phase networks with a neutral, since the phase-to-phase voltage exceeds the
operating range of the instrument (95...300 V) on three-phase networks with no neutral.
In the fault voltage test function (
), the connections of the network are automatically checked in
order to test for the possible inversion of N-PE.
WARNING: in this case, in the event of an insulation fault on the installation, the RCD will
not work.
To start a new measurement, press the “TEST” button again.
To go back to the display of the network voltage U
L-N
, turn the selector switch or press CHANGE or
SELECT.
CAUTION! To ensure that the RCD is working properly, the first measurement on each circuit
(power outlet, appliance…) must be a test “with tripping”. Only the measurement
points connected in parallel can be tested “without tripping”.
When testing three-phase protective RCD’s, each phase (L
1
, L
2
, L
3
) should be checked in relation to the
protective conductor PE, to ensure that all of the phases are correctly connected to the RCD.
- Fluctuations in the measured fault voltage values
If substantial differences between values are noted when making consecutive measurements, this
indicates that there are strong fluctuations in the network voltage.
In this case, you can make a measurement with the earth probe as described below:
- Measurements with the earth probe applicable in TT supply systems
In this case, the fault voltage is no longer derived from the Z
s
x I
∆
N
calculation, but is calculated from R
A
x I
∆
N
. Network interference has a much greater influence on Z
S
than on R
A
(since Z
S
is the loop going
through the transformer), so the value of U
F
is more precise if a probe is used.
For measurements with a probe, as well as the connections shown on the diagram, connect the probe
lead to the “S /
“ terminal on the instrument. The “ “ symbol comes up. The other end of the lead
should be connected to the earth with an earth testing rod.
Make sure to position the probe outside of any region carrying a potential - at a distance of approximately
20 m in relation to active earthing points. (see connection diagram). Make the measurement, read off the
earth value measured or save it. Move the probe to ±10% of the distance and repeat the measurement.
If the measurement remains unchanged, this means that the distance is sufficient. If the value does
change, move the probe until the value stabilises.
If it is not possible to plant a rod in the earth, the probe lead can be connected to an earthed neutral
conductor (N conductor). In this case, the measurement accounts for the transformer earth connection
resistance (as per DIN VDE 0100 max. 2
Ω
).
- Testing installations with a maximum fault voltage of 25 V (humid environments)
Before starting a test, bring up the U
L
voltage limit on the display with the MORE button and change the
limit, 25 V/50 V, with the CHANGE button.
- Comments on the selective RCD ( ) test procedure
The measurement procedure is the same as for the standard test, but the calculation of measured
values and the trip test (as per DIN VDE 0100) is carried out on the basis of the formula R
A
= U
L
/ 2 x I
∆
N
(the trip test is done with twice the nominal fault current).
Also, a 30 second pause is added between the initial tests (at I < 40% I
∆
N
) and the trip test. A counter
comes up on the screen and counts down the seconds from 30 to 0. When 0 comes up, the RCD test is
started. This 30 wait can be shortened by pressing “TEST” again.
The reason for this pause is due to the design of selective RCD’s, which are not sensitive to overvoltages
able to intervene on networks. They have an energy accumulation capacity, which charges up following
initial tests made with the instrument
(with I < 40% I
∆
N
).
The trip time of this sort of RCD is then changed.
This “hysteresis” effect is corrected over the discharge time of 30 s.