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6.15
Date Code 20171006
Instruction Manual
SEL-400 Series Relays
Autoreclosing
Two-Circuit-Breaker Autoreclosing
Choose Circuit Breaker BK1 as the leader and Circuit Breaker BK2 as the fol-
lower. If Circuit Breaker BK1 is out of service (for maintenance, for example),
the relay can automatically make Circuit Breaker BK2 the leader.
The relay freezes the leader, follower, and number of active circuit breaker desig-
nations during an autoreclose cycle. If the logic receives another reclose initia-
tion, the relay reevaluates the leader, follower, and number of active circuit
breaker designations. The logic considers a circuit breaker out of service if the
circuit breaker goes to lockout, and declares a circuit breaker to be in service as
soon as the circuit breaker closes and is no longer in lockout.
Leader Logic
Relay settings SLBK1 (Leader Breaker = Breaker 1) and SLBK2 (Leader
Breaker = Breaker 2) SEL
OGIC
control equations determine the criteria for relay
selection of the active leader. Set SLBK1 := 1 to select Circuit Breaker BK1 as
the leader; set SLBK2 := 1 to select Circuit Breaker BK2 as the leader. SLBK1
has priority over SLBK2; if you set both settings to 1 or both to 0, Circuit
Breaker BK1 is the leader.
Circuit Breaker BK1 is the leader for the following conditions:
➤
BK1 is the only circuit breaker in service
➤
BK1 and BK2 are in service and BK1 is selected as the leader
(SLBK1 := 1)
➤
BK1 and BK2 are in service and the setting combination SLBK1 := 0
and SLBK2 := 1 is not in effect
Circuit Breaker BK2 is the leader for the following conditions:
➤
BK2 is the only circuit breaker in service
➤
BK1 and BK2 are in service and BK2 is selected as the leader
(SLKBK1 := 0 and SLBK2 := 1)
➤
If neither circuit breaker is in service, there is no leader
The following three Relay Word bits describe which circuit breaker is the leader:
➤
LEADBK0, No Breaker In Service
➤
LEADBK1, Leader Breaker = Breaker 1
➤
LEADBK2, Leader Breaker = Breaker 2
The relay loads the corresponding circuit breaker settings into the leader Relay
Word bits (LEADBK0, LEADBK1, and LEADBK2). If there is no leader (no cir-
cuit breaker is active), the relay loads a logical 0 into LEADBK1 and LEADBK2,
and a logical 1 into LEADBK0.
Figure 6.2
Multiple Circuit Breaker Arrangement
Bus 1
(Leader)
(Follower)
Line
Bus 2
BK2
BK1
Summary of Contents for SEL-421-4
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