6.21
Date Code 20171006 Instruction Manual SEL-400 Series Relays
Autoreclosing
Two-Circuit-Breaker Autoreclosing
79CY3 Cycle State
The autoreclose logic receives a three-pole initiation. Table 6.15 defines the logi-
cal state of the autoreclose logic for this example during the three-pole autore-
close cycle.
BK2 closes as the follower when BK1 successfully closes (after timer TBBKD).
Lockout State
Circuit Breaker BK1 must close before Circuit Breaker BK2. If Circuit Breaker
BK1 fails to close and goes to lockout, then Circuit Breaker BK2 goes to lockout
as well because BK2 cannot close as the follower and cannot dynamically
become the leader. Table 6 .1 6 defines the logical state of the autoreclose logic for
this example following the unsuccessful reclose attempt.
FOLBK0 No Follower Breaker 0
FOLBK1 Follower Breaker = Breaker 1 0
FOLBK2 Follower Breaker = Breaker 2 1
Table 6.14 Example Three: Reset State (Sheet 2 of 2)
Relay Word Bit Description Logical State
Table 6.15 Example Three: Three-Pole Cycle State
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
FOLBK0 No Follower Breaker 0
FOLBK1 Follower Breaker = Breaker 1 0
FOLBK2 Follower Breaker = Breaker 2 1
Ta b l e 6 .16 Ex a m p l e Th r e e : L o c kout S tate, B K
Relay Word Bit Description Logical State
NBK0 No Active Breakers in Reclose Scheme 1
NBK1 One Breaker Active in Reclose Scheme 0
NBK2 Two Active Breakers in Reclose Scheme 0
LEADBK0 No Leader Breaker 1
LEADBK1 Leader Breaker = Breaker 1 0
LEADBK2 Leader Breaker = Breaker 2 0
FOLBK0 No Follower Breaker 1
FOLBK1 Follower Breaker = Breaker 1 0
FOLBK2 Follower Breaker = Breaker 2 0
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