R.2.23
Date Code 20111215 Reference Manual SEL-421 Relay
Auto-Reclosing and Synchronism Check
Two-Circuit-Breaker Auto-Reclosing
Figure 2.4 Leader/Follower Selection by Relay Input
Tab le 2.18 defines the logical state of the auto-reclose logic for this example
prior to the initiation of an auto-reclose cycle. These conditions are frozen
during an auto-reclose cycle. The SEL-421 auto-reclose logic can unfreeze
these conditions if the relay receives another initiation.
Enable Auto-Reclose
Logic for Two Circuit
Breakers
Three-Pole Trip Circuit Breakers
The initial settings necessary to enable auto-reclose for two three-pole trip
circuit breakers are shown in Table 2.19.
Table 2.18 Two Circuit Breakers: Circuit Breaker BK1 Out of Service
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
Bus 1
(Leader)
Line
to IN106 to IN107
Out of Service
(maintenance)
Bus 2
BK2
BK1
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