[fo_bsp2, 1, en_US]
Set Matching ratio Vph / VN = 0.866.
Interpretation of the result:
The zero-sequence voltage calculated from the phase-to-ground voltage is 57.73 V (= 100V/√3). The meas-
ured residual voltage is 200 V. The calculated adaptation factor is 0.866. The measured residual voltage is
converted to a zero-sequence voltage inside the device:
[fo_umrechnung2, 2, en_US]
NOTE
During the ground-fault test, the set adaptation factor can be checked by comparing the operational meas-
ured values. The operational measured values contain the calculated zero-sequence voltage V
0 sec
and the
measured residual voltage V
N sec
. Proceed with the compilation as follows:
The Matching ratio Vph / VN parameter is significant for the following functions:
•
Overvoltage protection with zero-sequence voltage/residual voltage
•
Measured-value supervision
•
Scaling of the faulty and measured values
Parameter: VT connection
•
Default setting (_:8911:104) VT connection = 3 ph-to-gnd volt. + VN
The parameter VT connection shows the connection type of the voltage transformer for the 3-phase
voltage measuring point. The parameter can be found in the DIGSI 5 project tree under Name of the device
→ Settings → Power system → Measuring point V 3-phase. You cannot change the connection type of the
voltage transformer in the power-system data.
You can change the connection type of the voltage transformer only under measuring point routing in
DIGSI 5. Under Name of the device → Measuring-points routing → Voltage measuring points, select the
desired connection type under Connection type. The following types of connections are possible:
•
3 ph-to-gnd volt. + VN
•
3 ph-to-gnd voltages
•
3 ph-to-ph volt. + VN
•
3 ph-to-ph voltages
•
2 ph-to-ph volt. + VN
•
2 ph-to-ph voltages
•
2 ph-to-gnd volt. + VN
•
2 ph-to-gnd voltages
Depending on the connection type selected, you must route the measured values to the terminals of the
voltage measuring point in DIGSI 5. You can find connection examples for voltage transformers in the chapters
Function-Group Types
5.1 Power-System Data
SIPROTEC 5, High-Voltage Bay Controller, Manual 185
C53000-G5040-C015-9, Edition 11.2017
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