Siemens siprotec 7SA522, Руководство пользователя

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Functions
6-8
7SA522 Manual
C53000-G1176-C119-2
When connected to the e-n winding of a set of voltage transformers, the voltage
transformation ratio of the voltage transformers is usually:
In this case the factor
8SK8GHOWD
(address
,
matching ratio for the secon-
dary nominal voltages of phase voltage transformer and open-delta voltage) must
be set to 3/
√
3 =
√
3
≈
1.73. For other transformation ratios, e.g. when the displace-
ment voltage is generated by means of interposing transformers, this factor must
be adjusted accordingly. This factor is of importance for the monitoring of the meas-
ured 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. Fig A-15. In this case address
is set to:
8WUDQV
IRUPHU
=
8V\QFWUDQVI
If the transformation ratio differs from that of the line voltage transformers this can
be adapted with the setting in address
8OLQH8V\QF
. In address
8V\QFFRQQHFW
, 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 reference voltages used for synchro-
nism check are not separated by a device that causes a relative phase shift of the
measured voltages (e.g. star-delta power transformer) then the parameter in ad-
dress
M8V\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
$GGLWLRQDO6HWWLQJV
. The phase an-
gle 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 cor-
responds to the angle of
8V\QF
measured in counter-clockwise direction.
Example (refer also to Figure 6-9):
Busbar 400kV primary
110 V secondary
Feeder 220 kV primary
100 V secondary
Transformer 400 kV / 220 kV
Vector group Yd(n) 5
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.
°
.
Since the busbar voltage transformer provides 110 V secondary with nominal pri-
mary voltage and the line voltage transformer only 100 V under the same condi-
tions, this difference must also be considered:
8OLQH8V\QF
= 100 V/ 110 V =
U
Nprim
3
------------------
U
Nsec
3
----------------
U
Nsec
3
----------------
⁄ ⁄