Functions
2.18 Synchronism and Voltage Check (optional)
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
354
Closing under asynchronous system conditions
Before releasing a closing command under asynchronous conditions, the following conditions are checked:
• Is the busbar voltage above the setting value Live Volt. Thr. but below the maximum voltage Umax?
• Is the feeder voltage above the setting value Live Volt. Thr. but below the maximum voltage Umax?
• Is the voltage difference |U
sy1
– U
sy2
| within the permissible tolerance AR maxVolt.Diff or MC
maxVolt.Diff?
• Are the two frequencies f
sy1
and f
sy2
within the permitted operating range f
N
± 3Hz?
• Does the frequency difference |f
sy1
– f
sy2
| lie within the permissible tolerance AR maxFreq.Diff or MC
maxFreq.Diff?
When the check has been terminated successfully, the device determines the next synchronizing time from the
angle difference and the frequency difference. The close command is issued at synchronization time minus the
operating time of the circuit breaker.
2.18.2 Setting Notes
Preconditions
When setting the general power system data (Power system data 1, refer to Section 2.1.2.1) a number of pa-
rameters regarding the measured quantities and the operating mode of the synchronism check function must
be applied.
This concerns the following parameters:
203 Unom PRIMARY primary rated voltage of the voltage transformers of the protection functions
(phase-to-phase) in kV, measuring point U
sy1
;
204 Unom SECONDARY secondary rated voltage of the protection functions (phase-to-phase) in V,
measuring point U
sy1
;
210 U4 transformer voltage measuring input U
4
must be set to Usy2 transf.;
212 Usy2 connection voltage connection of measuring point U
sy2
(e.g. U
L1–L2
),
214 Ï• Usy2-Usy1 phase displacement between the voltages U
sy2
and U
sy1
if a transformer is
switched in between;
215 Usy1/Usy2 ratio ratio between the secondary voltage U
sy1
and voltage U
sy2
under nominal
condition;
230 Rated Frequency the operating range of the synchronism check refers to the nominal frequen-
cy of the power system (f
N
± 3 Hz);
1103 FullScaleVolt. nominal operational voltage of the primary power system (phase-phase) in
kV;
and, if switching under asynchronous system conditions is allowed,
239 T-CB close the closing time of the circuit breaker.
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