Siemens siprotec 7SA6 User Manual page 190

Functions
6-8
Address  is then set to: 8 WUDQVIRUPHU = 8GHOWD WUDQVI.
When connected to the e-n winding of a set of voltage transformers, the voltage
transformation ratio of the voltage transformers is usually:
⁄ ⁄
U U U
Nprim Nsec
----------------- - --------------- - --------------- -
3 3
In this case the factor 8SK  8GHOWD (address , matching ratio for the
secondary nominal voltages of phase voltage transformers and open-delta voltage)
must be set to 3/√3 = √3 ≈ 1.73. For other transformation ratios, e.g. when the
displacement voltage is generated by means of interposing transformers, this factor
must be adjusted accordingly. This factor is of importance for the monitoring of the
measured values and the scaling of the measurement and disturbance recording
signals.
• In case the busbar voltage is connected to the U4 input for synchronism check, refer
also to Appendix A, e.g. Figure A-15. In this case address  is set to: 8
WUDQVIRUPHU = 8V\QF WUDQVI
If the transformation ratio differs from that of the line voltage transformers this can
be adapted with the setting in address  8OLQH  8V\QF. In address 
8V\QF FRQQHFW, the type of voltage used for synchronism check is configured.
According to this setting, the device automatically selects the appropriate phase to
phase or phase to ground voltage. If the two voltages used for synchronism check
— i.e. line voltage and busbar voltage — are not separated by a unit that causes a
relative phase shift of the measured voltages (e.g. star-delta power transformer)
then the parameter in address  ϕ 8V\QF8OLQH is not required. If however a
transformer with a vector group unequal to zero separates the two voltage sources,
this setting must be used to compensate the phase shift according to the vector
group of the transformer. This setting is only available in DIGSI 4 under
$GGLWLRQDO 6HWWLQJV. The phase angle setting is defined as follows: place
Usync at zero degrees as reference voltage, draw in Uline with the correct phase
relationship relative to Usync; the setting corresponds to the angle of 8V\QF
measured in counter-clockwise direction.
Example (refer also to Figure 6-9):
Busbar
Feeder
Transformer
Vector group
The vector group of the transformer defines the phase shift of the voltage from the
high voltage to the low voltage side (Vector group 5 corresponds to a phase shift of
5 x 30° in the clockwise direction of the low voltage side relative to the high voltage
side). In this example, the feeder voltage is connected to the low voltage side of the
transformer. If Usync (busbar or high voltage side) is placed at zero degrees, then
Uline is at 5 x 30° in the clockwise direction, i.e. at –150°. According to the definition
for the setting, the angle from 8V\QF to 8OLQH in the counter-clockwise direction
must be taken, i.e. °.
Address $:
Since the busbar voltage transformer provides 110 V secondary with nominal
primary voltage and the line voltage transformer 100 V under the same conditions,
Nsec
3
400kV primary
110 V secondary
220 kV primary
100 V secondary
400 kV / 220 kV
Dy(n) 5
ϕ 8V\QF8OLQH = 360° - 150° = 210°
7SA6 Manual
C53000-G1176-C133-1