NOTE
You do not need to change the parameters Winding configuration and Vector group numeral
for the example application described. You must establish the phase reference by way of the vector group
if the capacitor bank is in a delta connection.
You can find further information in the device manual 7UT8, chapter 6.2.3 Description Vector-Group
Correction.
Parameter: Winding configuration
•
Default setting (_:1781:15571:104) Winding configuration = Y (Wye)
With the parameter Winding configuration, you set D (Delta) for a delta connection. A further star-
connection setting option is Y (Wye). The parameter Winding configuration is relevant for the differen-
tial protection function. You do not need to change this setting for the example application described.
Parameter: Vector group numeral
•
Default setting (_:1781:15571:100) Vector group numeral = 0
This parameter is used to account for phase-angle rotation, which is expressed by a number.
Phase-angle rotation 0° 30° 60° 90° 120° 150° 180° 210° 240° 270° 300° 330°
Vector group
numeral
0 1 2 3 4 5 6 7 8 9 10 11
In the function group, the following information is displayed additionally in the setting sheet:
•
Side number
•
Identification of the measuring points used
•
Adaptation factor for the 3-phase measuring point (with reference to the side)
You can set each Vector group numeral from 0 to 11 to the extent possible. Thus, for example, only even
numbers are possible for the vector groups Yy and Dd and only odd numbers are possible for Yd and Dy.
You do not need to change this setting for the example application described.
Function Group Capacitor Bank diff
Proceed with the following settings in the Capacitor bank diff function group for the I-DIFF function:
Parameter: Threshold (Setting the Characteristic-Curve Parameters)
•
Default setting (_:11041:3) Threshold = 0.20 I/Irated,obj
You set the pickup threshold for the differential current with this parameter. This is the total current flowing
into the protection range during a short circuit, regardless of how it is distributed on the sides of the protected
object. The pickup value is relative to the rated current of the protected object. The default setting of 0.20
I/Irated,obj is a practical value between sensitivity and possible disturbing influence.
Parameter: Intersection 1 Irest
•
Default setting (_:11041:101) Intersection 1 Irest = 0.67 I/Irated,obj
The maximum current of the measuring point is used as restraint current. If you have to expect dynamic trans-
mission faults of the current transformer even with small currents, half of the rated current is an appropriate
setting value.
Parameter: Slope 1
•
Default setting (_:11041:100) Slope 1 = 0.30
Capacitor Bank Protection
7.8 Differential Protection for Capacitor Banks
SIPROTEC 5, Overcurrent Protection, Manual 1063
C53000-G5040-C017-8, Edition 07.2017
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