![Schweitzer Engineering Laboratories SEL-421-4 Instruction Manual Download Page 996](http://html.mh-extra.com/html/schweitzer-engineering-laboratories/sel-421-4/sel-421-4_instruction-manual_1216726996.webp)
6.20
SEL-400 Series Relays
Instruction Manual
Date Code 20171006
Autoreclosing
Two-Circuit-Breaker Autoreclosing
When BK1 successfully recloses, BK2 closes as the follower after timer TBBKD
(Time Between Breakers for ARC).
If BK1 goes to lockout during a reclose cycle (after BKCFD time), then BK2 will
close as the follower. After timer 3PRCD (Three-Pole Reclaim Time Delay)
expires, the recloser enters the reset state for BK2 (BK2RS). The recloser dynam-
ically recalculates the leader and follower circuit breakers. BK2 becomes the
leader with Relay Word bits LEADBK2, FOLBK0, and NBK1 asserted (see
). When BK2 becomes the leader, the recloser immediately issues the
close command to BK2 and does not add any additional SPOID or 3POID inter-
val time.
Example Three: BK2 as Conditional Follower
One method to program BK2 for closing only after a successful BK1 close is to
set SLBK1/SLBK2/FBKCEN as in
Reset State
Prior to receiving initiation for a three-phase fault, the autoreclose logic resets for
both circuit breakers.
defines the logical state of the autoreclose logic
for this example prior to the initiation of an autoreclose cycle.
Table 6.12
Example Two: Final Reset State
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
Table 6.13
Leader/Follower Selection
Setting Label
Value
SLBK1
1
SLBK2
0
FBKCEN
52AA1
Table 6.14
Example Three: Reset State (Sheet 1 of 2)
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
Summary of Contents for SEL-421-4
Page 6: ...This page intentionally left blank ...
Page 14: ...This page intentionally left blank ...
Page 30: ...This page intentionally left blank ...
Page 104: ...This page intentionally left blank ...
Page 128: ...This page intentionally left blank ...
Page 536: ...This page intentionally left blank ...
Page 584: ...This page intentionally left blank ...
Page 616: ...This page intentionally left blank ...
Page 696: ...This page intentionally left blank ...
Page 750: ...This page intentionally left blank ...
Page 755: ...Instruction Manual PM400 01 NB SEL 400 Series Relays Instruction Manual 20171006 ...
Page 776: ...This page intentionally left blank ...
Page 932: ...This page intentionally left blank ...
Page 976: ...This page intentionally left blank ...
Page 1024: ...This page intentionally left blank ...
Page 1038: ...This page intentionally left blank ...
Page 1064: ...This page intentionally left blank ...
Page 1128: ...This page intentionally left blank ...
Page 1206: ...This page intentionally left blank ...
Page 1316: ...This page intentionally left blank ...
Page 1350: ...This page intentionally left blank ...
Page 1464: ...This page intentionally left blank ...
Page 1468: ...This page intentionally left blank ...
Page 1492: ...This page intentionally left blank ...
Page 1518: ...This page intentionally left blank ...