R.2.17
Date Code 20111215 Reference Manual SEL-421 Relay
Auto-Reclosing and Synchronism Check
Two-Circuit-Breaker Auto-Reclosing
sets circuit breaker designations. The leader/follower designation can
dynamically change in the cycle if the leader circuit breaker goes to lockout
and FBKCEN is asserted.
Set the initial leader/follower designation and follower close conditions with
settings SLBK1 (Lead Breaker = Breaker 1), SLBK2 (Lead Breaker =
Breaker 2), and FBKCEN (Follower Breaker Closing Enable). Table 2.5
shows the permutations of these settings.
Circuit Breaker BK1 is always the leader if SLBK1 is asserted and BK1 is not
locked out. Circuit Breaker BK2 is the leader if SLBK2 is asserted, BK2 is not
locked out, and SLBK1 is not asserted. The second circuit breaker can become
the leader when the leader is locked out.
Setting FBKCEN does not pick the follower, but decides when the second
circuit breaker can reclose. If the leader goes to lockout, then the follower
goes to lockout if FBKCEN := 0. If, however, the leader is manually opened,
the follower breaker can become the leader (after being manually closed) and
can close via a reclose cycle if FBKCEN := 1. If you want the follower
breaker to close only for specific conditions, use the enable settings to force
this close requirement. For example, Circuit Breaker BK2 can dynamically
become the leader if BK1 is locked out and BK2 is closed. If you do not want
BK2 to become the leader, set FBKCEN := 52AA1. Also see Example One:
No Follower on page R.2.18 for another method to prevent BK2 from
becoming the leader.
Table 2.5 Dynamic Leader/Follower Settings
SLBK1 SLBK2 FBKCEN Comments
0 0 0 BK1 is the leader; BK2 is the leader only if BK1 LO
and BK2 is closed. BK2 will not close as the follower
upon successful close of leader BK1.
0 0 1 BK1 is the leader; BK2 is the leader only if BK1 LO
and BK2 is closed. BK2 will close as the follower if
BK1 LO after BKCFD. BK2 will close as the fol-
lower upon successful close of the leader BK1.
0 1 0 BK2 is the leader; BK1 is the leader only if BK2 LO
and BK1 is closed. BK1 will not close as the follower
upon successful close of leader BK2.
0 1 1 BK2 is the leader; BK1 is the leader only if BK2 LO.
BK1 will close if BK2 LO after BKCFD. BK1 will
close as the follower after TBBKD upon successful
close of the leader BK1.
1 0 0 BK1 is the leader; BK2 is the leader only if BK1 LO
and BK2 is closed. BK2 will not close as the follower
upon successful close of leader BK1.
1 0 1 BK1 is the leader; BK2 is the leader only if BK1 LO
and BK2 is closed. BK2 will close as the follower if
BK1 LO after BKCFD. BK2 will close as the fol-
lower upon successful close of the leader BK1.
1 1 0 Same as 1/0/0.
1 1 1 Same as 1/0/1.
1 0 52AA1 BK1 is the leader; BK2 to LO if BK1 LO. BK2 will
close as the follower after TBBKD upon successful
close of the leader BK1.
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