Siemens 7SR157 Argus, Manual

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Chapter 1 - 7SR157 Description of Operation
© 2022 Siemens Protection Devices Limited Chapter 1 - Page 23 of 38
Section 4:
Control Functions
4.1 25 Check Sync
Check Synchronising is enabled via 25 Check Sync in the CHECK SYNC MENU.
Check Synchronising sets 25 InSyncCS and 25 Check Sync Close outputs when the Line and Bus voltages are
healthy and synchronised.
The phase angle tolerance between the Line and Bus voltages for being synchronised is set by 25 Check Sync
Angle setting. The synchronised conditions must be held for a minimum time of 25 Check Sync Timer setting.
An optional setting 25 Check Sync Slip may be applied to limit Slip Frequency; this selection is made by
changing the 25 Check Sync Slip Freq setting.
Check Synchronising requires 25 Voltage Check to be set. 25 Voltage Check is an output derived from voltage
logic, indicating that the line and bus voltages are healthy. Figure 4-1 illustrates the Voltage Check Function logic.
Figure 4-1 Voltage Check Function logic
The 25 Check Sync Close output will stay on for a minimum time of 100ms and for the whole duration of the time
that the check synchronizing conditions are met. Unlike System Sync Close and Close On Zero Close , which
are pulsed outputs.
The Check Sync inhibit command, Check Sync Inhibit will inhibit a 25 Check Sync Close output from being set.
Check Sync Inhibit will not inhibit the 25 InSyncCS or 25 CS In Progress outputs from being set.
There are two modes of operation, Auto and Manual. The selection is made by changing 25 Check Sync Enable
in the CHECK SYNC MENU.
AUTO : 25 Check Sync Close output is set when the Check synchronizing conditions are met.
MANUAL : 25 Check Sync Close output is set when Check synchronizing conditions are met and a manual
close command is received, via Start Check Sync input.
The Reset 25 Sync input resets the following outputs: 25 in Sync , 25 InSyncCS , 25 InSyncSS , 25 InSyncCOZ ,
25 Check Sync Close , 25 System Sync Close , 25 COZ Close , 25 CS In Progress , 25 SS In Progress , 25
COZ In Progress .
For the relay to set the 25 Check Sync Close output the following conditions have to be met:

25 Check Sync Angle – the phase difference between the line and bus voltages has to be less than
the 25 Check Sync Angle setting value. Whilst within the limits the phase angle can be increasing or
decreasing and the element will still issue a valid close signal.