Siemens 7SR12 Argus Manual page 68

7SR11 & 7SR12 Description Of Operation
79 Sequence Co-Ord
Notes on the 'Lockout' State
The Lockout state can be reached for a number of reasons. Lockout will occur for the following: -
•
At the end of the 79 Sequence Fail Timer.
•
At the end of the Reclaim timer if the CB is in the open position.
•
A protection operates during the final Reclaim time.
•
If a Close Pulse is given and the CB fails to close.
•
The 79 Lockout binary input is active.
•
At the end of the 79 Reclose Blocked Delay due to presence of a persistent Block signal.
•
When the 79 Elem HS Trips to Lockout count is reached.
•
When the 79 Elem Delayed Trips to Lockout count is reached.
An alarm output is provided to indicate last trip to lockout.
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: -
•
By a Manual Close command, from fascia, comms or Close CB binary input.
•
By a 79 Reset Lockout binary input, provided there is no signal present that will cause Lockout.
•
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.
•
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.
•
By the CB Closed binary input, provided there is no signal present which will cause Lockout.
The Lockout condition has a delayed drop-off of 2s. The Lockout condition can not be reset if there is an active
lockout input.
Chapter 1 Page 64 of 88
When set to Enabled the Relay will co-ordinate its sequence and shot count such that
it automatically keeps in step with downstream devices as they advance through their
sequence. The Relay detects that a pickup has operated but has dropped-off before its
associated time delay has expired, it then increments its Shot count and advances to
the next stage of the auto-reclose sequence without issuing a trip, this is repeated as
long as the fault is being cleared by the downstream device such that the Relay moves
through the sequence bypassing the INST Trips and moving on to the Delayed Trip to
maintain Grading margins.
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