Please note that, when using the compensated measurands as well as the automatic compensation, the
currently measured current unbalance (that resulted in the threshold being exceeded) is gradually compen-
sated. This means that even in case of a constantly existing unbalance in the primary system, the compen-
sated measurand becomes gradually lower and may therefore fall below the threshold again at some time.
The timing depends on by how much the threshold is exceeded.
For this reason and under those conditions, long time delays must not be set, see also chapter 7.5.4.2 Applica-
tion and Setting Notes.
This effect does not occur if manual compensation or the non-compensated measurand is used.
Blocking While Charging
In order to prevent pickup as a consequence of the charging process, the I> stage is implicitly blocked for
250 ms by setting
I
unbal.,comp.
to 0 A, after capacitor energizing has been detected. Blocking only takes place if
the stage operates with compensated unbalanced values.
Fault-Location Information
When picking up, the stage provides information about the faulty group of the capacitor bank. If the location
can be safely determined, the corresponding indication
Fault position group 1
or
Fault position
group 2
is issued.
Both indications also contain the information about the faulty phase. If the capacitor is implemented with
2 neutral points, the following definition is assumed:
[dwfehlerortinf_iunsy1ph-070714-01, 1, en_US]
Figure 7-28 Definition for the Fault-Location Information
The black dot indicates the orientation of the current transformer. For the connection of the current trans-
former shown in the previous figure, the following definition applies:
•
Group 1: C1
•
Group 2: C2
In order to determine the fault location (group 1 or 2) correctly, use the parameter Capacitor element
type (in FB General of the Capacitor bank function group) to tell the device whether the elements of the
capacitor bank have internal fuses or not.
Non-Compensated Status
If no compensated values are available and the stage has been set to use such values, the stage will be
blocked. The readiness of the stage turns to
Warning
. This condition will be reported on the function stage
(indication
Alg. not compensated
).
Application and Setting Notes
Parameter: Measured value
•
Default setting (_:16231:100) Measured value = compensated
7.5.4.2
Capacitor Bank Protection
7.5 Current-Unbalance Protection for Capacitors, 1-Phase
SIPROTEC 5, Overcurrent Protection, Manual 1013
C53000-G5040-C017-8, Edition 07.2017
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