P.4.22
SEL-411L Relay Protection Manual Date Code 20151029
Autoreclosing and Synchronism-Check
Two-Circuit-Breaker Autoreclosing
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 4.16 defines the logical state of the
autoreclose logic for this example following the unsuccessful reclose attempt.
Example Four: Input Selection of Leader
Figure 4.4 illustrates a circuit breaker-and-a half configuration for this
particular example. The leader and follower selection settings are shown in
Table 4.17. Circuit Breaker BK1 is out of service for maintenance and
Disconnect Switch 1 is open.
Figure 4.4 Leader/Follower Selection by Relay Input
Table 4.18 defines the logical state of the autoreclose logic for this example
prior to the initiation of an autoreclose cycle. These conditions are frozen
during an autoreclose cycle. The autoreclose logic can unfreeze these
conditions if the relay receives another initiation.
Ta b l e 4.1 6 E xa m p le T h re e : Lo c ko u t S ta te, B K 1
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
Table 4.17 Leader/Follower Selection
Setting Label Setting
SLBK1 IN206 (Disconnect 1 a contacts)
SLBK2 IN207 (Disconnect 2 a contacts)
FBKCEN 0
Bus 1
(Leader)
Line
to IN206 to IN207
Out of Service
(maintenance)
Bus 2
BK2
BK1
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