Siemens 7SR224 Technical Manual page 45

79 Check Synchronising during the Deadtime will start the Check Synchronising before the completion of the
deadtime if the dead state of the line or bus becomes live during the deadtime. This
restoration of Live voltage state indicates that the remote end circuit breaker has
reclosed and therefore it is not necessary to delay the CB close until the deadtime
expires. This feature can be disabled if it is not required.
79 LO Line VT Fail will Lockout the autoreclose feature if the Line voltage is dead whilst the Bus voltage is live
when the circuit breaker is closed.
79 LO Bus VT Fail will Lockout the autoreclose feature if the Bus voltage is dead whilst the Line voltage is live
when the circuit breaker is closed.
Notes on the 'Lockout' State
The Lockout state can be reached for a number of reasons. Lockout will occur for the following: -
1. 79 Sequence Fail Timer.
2. At the end of the At the end of the Reclaim timer if the CB is in the open position.
3. A protection operates during the final Reclaim time.
4. If a Close Pulse is given and the CB fails to close.
5. The 79 Lockout binary input is active.
6. At the end of the 79 Reclose Blocked Delay due to presence of a persistent Block signal.
7. When the 79 Elem HS Trips to Lockout count is reached.
8. When the 79 Elem Delayed Trips to Lockout count is reached.
Once lockout has occurred, an alarm (79 Lockout) is issued and all further Close commands, except manual
close, are inhibited.
If the Lockout command is received while a Manual Close operation is in progress, the feature is immediately
locked-out.
Once the Lockout condition has been reached, it will be maintained until reset. The following will reset lockout: -
1. By a Manual Close command, from fascia, comms or Close CB binary input.
2. By a 79 Reset Lockout binary input, provided there is no signal present that will cause
Lockout.
3. At the end of the 79 Minimum LO Delay time setting if 79 Reset LO by Timer is selected
to ENABLED, provided there is no signal present which will cause Lockout.
4. Where Lockout was entered by an A/R Out signal during an Autoreclose sequence then
a 79 In signal must be received before Lockout can reset.
5. By the CB Closed binary input, provided there is no signal present which will cause
Lockout.
6. The Lockout condition has a delayed drop-off of 2s.
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7SR224 Argus Description of Operation
Chapter 1 Page 43 of 70