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Example:
Transformer Yy6d5
For the Y end set: VECTOR GROUP I = 0,
For the y end set: VECTOR GROUP I = 6,
For the d end set: VECTOR GROUP I = 5.
If a different winding is selected as reference winding, e.g. the d winding, this has to be considered accordingly:
For the Y end set: VECTOR GROUP I = 7 (12 - 5),
For the y end set: VECTOR GROUP I = 1 (6 - 5),
For the d end set: VECTOR GROUP I = 0 (5 - 5 = 0 = reference side).
Address 1161 VECTOR GROUP U is normally set to the same value as address 1162 VECTOR GROUP I.
If the vector group of the transformer is adapted with external means, e.g. because there are matching trans-
formers in the measuring circuit that are still used, set VECTOR GROUP I = 0 at all ends. In this case the dif-
ferential protection operates without proper matching computation. However, the measuring voltages beyond
the transformer would then not be adapted in the device and therefore not be calculated and displayed correct-
ly. Address 1161 VECTOR GROUP U eliminates this deficit. Set the correct vector group of the transformer ac-
cording to the above-mentioned considerations.
Address 1162 VECTOR GROUP I is therefore relevant for the differential protection whereas address 1161
VECTOR GROUP U serves as a basis for the calculation of the measured voltages beyond the transformer.
At address 1163 TRANS STP IS you can enter whether the power transformer starpoint facing the device is
earthed or not. If the starpoint is earthed, the device will eliminate the zero sequence current of the relevant
side, since this zero sequence current can otherwise cause a spurious tripping in case of a ground fault outside
of the protected zone.
General Line Data of the Distance Protection
The information under this margin heading apply only to cases where the distance protection has been config-
ured as the main function or as a backup protection of the differential protection.
The settings of the line data in this case refer to the common data which is independent of the actual distance
protection grading.
The line angle (address 1105 Line Angle) may be derived from the line parameters. The following applies:
where R
is the resistance and X
L
to the entire line length, or be per unit of line length as the quotient is independent of length. Furthermore, it
makes no difference whether the quotients are calculated with primary, or secondary values.
The line angle is of major importance, e.g. for earth impedance matching according to amount and angle or for
compounding in overvoltage protection.
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
the reactance of the protected feeder. The line parameters may either apply
L
Functions
2.1 General
57
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