31
Automatic connection identification is
not
possible with 3-phase measurement. The voltage and
current inputs must be connected in correct phase sequence.
Table 1 Connection types for current transformers in L1, L2 and L3
Connection type
Connection to voltage path
L/N – L
L/N – L
L/N – L
0
L1 – N
L2 – N
L3 – N
1
L1 – L3
L2 – L1
L3 – L2
2
N – L3
N – L1
N – L2
3
L2 – L3
L3 – L1
L1 – L2
4
L2 – N
L3 – N
L1 – N
5
L2 – L1
L3 – L2
L1 – L3
6
N – L1
N – L2
N – L3
7
L3 – L1
L1 – L2
L2 – L3
8
L3 – N
L1 – N
L2 – N
9
L3 – L2
L1 – L3
L2 – L1
10
N – L2
N – L3
N – L1
11
L1 – L2
L2 – L3
L3 – L1
Current transformer in:
↑
L1
↑
L2
↑
L3
6.5.2 Automatic identification of the connected capacitor stages
Having performed the connection identification procedure, the PQC then carries out the automa-
tic capacitor stage identification process (c/k setting). During this calibration procedure, all the
control contacts of the instrument are individually closed and opened again several times. This
identifies the switching sequence, but the procedure can take several minutes.
Later, during normal operation, the PQC checks its saved parameters at certain intervals of
time. If a capacitor stage fails, after a certain time this will be identified as a zero stage (with zero
power rating) and no longer used in the regular control process. All zero stages are switched in
again from time to time to check their power rating. If a capacitor stage has been retrofitted or
defective fuses have been replaced, the PQC will identify this after some time and the stage will
be reintegrated in the control process. We recommend, however, that a new calibration proce-
dure be initiated after a stage has been replaced.
Note: If the low voltage network is fed from several transformers arranged in parallel, the capa-
citor current is distributed between all the transformers. If the measurement is not carried out
via summation current transformers, the change in the current measurable by the PQC when
capacitor stages are switched in is too small, which may result in errors in the automatic capa-
citor stage identification process. We therefore recommend that in such situations the automatic
capacitor stage identification function be disabled and the appropriate parameters (c/k setting,
switching sequence and number of capacitor stages) programmed manually
[see Section 8.1]
.
