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Connection of the voltages
The device features four voltage measuring inputs, three of which are connected to the set of voltage trans-
formers. Various possibilities exist for the fourth voltage input U
• Connection of the U
Address 210 is then set to: U4 transformer = Udelta transf..
When connected to the e-n winding of a set of voltage transformers, the voltage transformation ratio of the
voltage transformers is usually:
The factor Uph/Udelta (secondary voltage, address 211 Uph / Udelta) must be set to 3/√3 = √3. For other
transformation ratios, i.e. the formation of the displacement voltage via an interconnected transformer set,
the factor must be corrected accordingly. This factor is of importance for the monitoring of the measured
values and the scaling of the measurement and disturbance recording signals.
• Connection of the U
Address 210 is then set to: U4 transformer = Usy2 transf..
If the voltage transformers for the protective functions U
transformer has to be connected to a busbar voltage U
transformers for the protective functions U
transformer must be connected to a feeder voltage.
If the transformation ratio differs, this can be adapted with the setting in address 215 Usy1/Usy2 ratio.
In address 212 Usy2 connection, the type of voltage connected to measuring point U
check is communicated to the device. The device then automatically selects the voltage at measuring point
U
. If the two measuring points used for synchronism check — i.e. feeder voltage transformer and busbar
sy1
voltage transformer — are not separated by devices that cause a relative phase shift, then the parameter in
address 214 ϕ Usy2-Usy1 is not required. This parameter can only be altered in DIGSI at Display Addi-
tional Settings. If, however, a power transformer is connected in between, its vector group must be adapt-
ed. The phase angle from U
Example: (see also Figure 2-3)
Busbar
Feeder
Transformer
The transformer vector group is defined from the high side to the low 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° (according to the vector group) in the clockwise direction, i.e. at –150°.
A positive angle is obtained by adding 360°:
Address 214: ϕ Usy2-Usy1 = 360° - 150° = 210°.
The busbar transformers supply 110 V secondary for primary operation at nominal value while the feeder
transformer supplies 100 V secondary. Therefore, this difference must be balanced:
Address 215: Usy1/Usy2 ratio = 100 V / 110 V = 0.91.
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009
input to the open delta winding e–n of the voltage transformer set:
4
input to perform the synchronism check:
4
to U
sy1
sy2
400 kV primary, 110 V secondary,
220 kV primary, 100 V secondary,
400 kV / 220 kV, vector group Dy(n) 5
:
4
are located on the outgoing feeder side, the U
sy1
. Synchronisation is also possible if the voltage
sy2
are connected on busbar side, in which case the additional U4
sy1
is evaluated positively.
Functions
2.1 General
4
for synchronism
sy2
31
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