P.4.11
Date Code 20151029 Protection Manual SEL-411L Relay
Autoreclosing and Synchronism-Check
Two-Circuit-Breaker Autoreclosing
At the leader CLOSE command, the recloser starts timer BKCFD (Breaker
Close Failure Delay). If the leader fails to close, the recloser sends the leader
to lockout after timer BKCFD expires. If the leader closes within the BKCFD
time, the recloser goes to SPRCD (Single-Pole Reclaim Time Delay) reclaim
timing if NBK1 is asserted, or prepares to close the follower circuit breaker if
NBK2 is asserted.
To close the follower circuit breaker, the recloser checks for two active circuit
breakers in the scheme. If NBK2 is asserted, the recloser checks for a single-
pole open on the follower and starts timer TBBKD (Time Between Breakers
For ARC). If multiple poles of the follower circuit breaker are open, the
recloser sends the follower to lockout BKnLO. When TBBKD expires, the
recloser closes the follower breaker if FBKCEN (Follower Breaker Closing
Enable) is asserted and supervisory condition SPnCLS is satisfied within the
duration of timer BKnCLSD. At the follower CLOSE command, the recloser
starts timer BKCFD (Breaker Close Failure Delay). If the follower fails to
close, the recloser sends the follower to lockout after timer BKCFD expires. If
the leader circuit breaker is not in lockout, the recloser begins timing SPRCD
reclaim time for the leader.
If the follower breaker closes successfully, the recloser starts the SPRCD
(Single-Pole Reclaim Time Delay) timer if 79BRCT (Block Reclaim Timer) is
not asserted.
SPRCD Reclaim Timing
The recloser determines subsequent state transitions during reclaim timing
according to the status of Relay Word bit SPLSHT (Single-Pole Reclose Last
Shot). When SPLSHT is asserted, the recloser forces all subsequent relay trips
to three-pole only mode.
SPLSHT Deasserted (Single-Pole Shot Remains). The recloser
exhibits four possible state transitions when SPLSHT is not asserted:
➤ If no further trip conditions occur and timer SPRCD expires,
the recloser returns to the reset states BKnRS.
➤ If a single-phase fault occurs while the SPRCD reclaim timer is
timing, then the recloser asserts SPARC if all single-pole
initiate conditions are satisfied and goes to the beginning of the
79CY1 cycle. The recloser then recalculates and freezes the
calculation for the number of active circuit breakers, the leader,
and the follower. The recloser then increments the shot counter
and begins the next open interval timer.
➤ If a multiphase fault occurs during the SPRCD reclaim time,
then the recloser asserts Relay Word bit 3PARC if all three-pole
reclose conditions are satisfied (E3PRn is logical 1, for
example) and recalculates the number of active circuit breakers,
the leader, and the follower before proceeding to the
autoreclose three-pole cycle state 79CY3.
➤ If a multiphase fault occurs during the SPRCD reclaim time,
SPLSHT is not asserted, and the three-pole reclose conditions
are not satisfied (E3PRn is logical 0, for example) and the
recloser exits the 79CY1 cycle state and goes to the lockout
state BKnLO.
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