Siemens 7SJ82 Manual page 985

If no counter stages are applied, Siemens recommends switching the automatic compensation off and using
the manual compensation. You can find more information on this recommendation in chapter
cation and Setting Notes
If the counter stages are applied, the automatic compensation must be switched on, otherwise the counting
function will not work.
Parameter: De-energ.time w/o comp.
•
Default setting (_:2311:104) De-energ.time w/o comp. = 2.00 s
In case of networks faults, the faulty phases are discharged. With the returning voltage after fault clearance,
charging takes place. For such conditions, Siemens recommends that no automatic full compensation takes
place in the affected phases. Otherwise, C-element defects occurring in this period (for example, because of
discharging stress due to network-fault inception) will not be detected.
With the parameter De-energ.time w/o comp., you define the duration of short de-energization after
which no automatic compensation takes place. The parameter must be set to a value larger than the slowest
fault-clearing time in your network plus a safety margin.
If the setting is set to 0 s, an automatic full compensation is carried out after each energizing detection.
Parameter: Normalization with Ic
•
Default setting (_:2311:100) Normalization with Ic = no
This parameter applies equally to all stages of the function.
Parameter Value
no
yes
Parameter: Thresh. defective C-elem.
•
Default (_:2311:102) Thresh. defective C-elem. = 0.030 A
Set the parameter Thresh. defective C-elem. to ensure that the jump in the unbalanced current
caused by the faulty C-element is detected. Information about occurring unbalanced current as a consequence
of single faulty C-elements will be provided by the manufacturer of the capacitor bank. Siemens recommends
to set the threshold value to approx. 75 % of the unbalanced current that occurs after the fault of the 1st C-
element.
Example 1: Information about the Unbalanced Current Available from the Manufacturer of the Capacitor Bank
Table 7-1
Number of Faulty C-Elements
0
1
2
3
...
Assumed current transformer ratio: 10 A/1 A
Primary unbalanced current if 1st C-element fails: 0.71 A
Secondary unbalanced current if 1st C-element fails: 0.071 A
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
(setting notes for the operate delay of the I> stage).
Description
Select this setting if you can safely assume that I
tional reasons or if you do not desire normalization of the unbalanced
current with I
Please consider that the protection sensitivity will decrease with decreasing
I .
c
Select this setting if you want to keep the sensitivity of the protection
stages constant during changes of I
Unbalanced Current, Depending on the Number of Faulty C-Elements
7.4 Current-Unbalance Protection for Capacitors, 3-Phase
.
c
.
c
Primary Unbalanced Current
0.00 A
0.71 A
1.47 A
2.29 A
...
Capacitor Bank Protection
7.4.4.2 Appli-
will not change for opera-
c
985