Schweitzer Engineering Laboratories SEL-421-4 - Page 994

6.18
SEL-400 Series Relays Instruction Manual Date Code 20171006
Autoreclosing
Two-Circuit-Breaker Autoreclosing
Reset State and 79CY3 Cycle State
Prior to receiving initiation for a three-phase fault, the autoreclose logic resets for
both circuit breakers. Table 6.7 defines the logical state of the autoreclose logic
for this example prior to the initiation of an autoreclose cycle.
Lockout State
Circuit Breaker BK1 fails to close when the first three-pole open interval expires
and goes to lockout. Circuit Breaker BK2 goes to lockout. Tabl e 6.8 defines the
logical state of the autoreclose logic at this point.
Reset State After Reclaim Time
Circuit Breaker BK2 is manually closed and now becomes active as the leader
after 3PMRCD (Manual Close Reclaim Time Delay). Subsequent reclosing
occurs with BK2. Tab le 6.9 defines the logical state of the autoreclose logic at
this point.
Table 6.6 Leader/Follower Selection
Setting Label Value
SLBK1 1
SLBK2 0
FBKCEN 0
Table 6.7 Example One: Reset and 79CY3 States
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 6.8 Example One: Lockout State
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