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.
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.
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
Table 6.16
Example Three: Lockout State, BK
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
Summary of Contents for SEL-421-4
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