6.20
SEL-400 Series Relays Instruction Manual Date Code 20171006
Autoreclosing
Two-Circuit-Breaker Autoreclosing
When BK1 successfully recloses, BK2 closes as the follower after timer TBBKD
(Time Between Breakers for ARC).
If BK1 goes to lockout during a reclose cycle (after BKCFD time), then BK2 will
close as the follower. After timer 3PRCD (Three-Pole Reclaim Time Delay)
expires, the recloser enters the reset state for BK2 (BK2RS). The recloser dynam-
ically recalculates the leader and follower circuit breakers. BK2 becomes the
leader with Relay Word bits LEADBK2, FOLBK0, and NBK1 asserted (see
Table 6.12). When BK2 becomes the leader, the recloser immediately issues the
close command to BK2 and does not add any additional SPOID or 3POID inter-
val time.
Example Three: BK2 as Conditional Follower
One method to program BK2 for closing only after a successful BK1 close is to
set SLBK1/SLBK2/FBKCEN as in Table 6.13.
Reset State
Prior to receiving initiation for a three-phase fault, the autoreclose logic resets for
both circuit breakers. Table 6.14 defines the logical state of the autoreclose logic
for this example prior to the initiation of an autoreclose cycle.
Table 6.12 Example Two: Final Reset State
Relay Word Bit Description Logical State
NBK0 No Active Breakers in Reclose Scheme 0
NBK1 One Breaker Active in Reclose Scheme 1
NBK2 Two Active Breakers in Reclose Scheme 0
LEADBK0 No Leader Breaker 0
LEADBK1 Leader Breaker = Breaker 1 0
LEADBK2 Leader Breaker = Breaker 2 1
FOLBK0 No Follower Breaker 1
FOLBK1 Follower Breaker = Breaker 1 0
FOLBK2 Follower Breaker = Breaker 2 0
Table 6.13 Leader/Follower Selection
Setting Label Value
SLBK1 1
SLBK2 0
FBKCEN 52AA1
Table 6.14 Example Three: Reset State (Sheet 1 of 2)
Relay Word Bit Description Logical State
NBK0 No Active Breakers in Reclose Scheme 0
NBK1 One Breaker Active in Reclose Scheme 0
NBK2 Two Active Breakers in Reclose Scheme 1
LEADBK0 No Leader Breaker 0
LEADBK1 Leader Breaker = Breaker 1 1
LEADBK2 Leader Breaker = Breaker 2 0
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