P.4.17
Date Code 20151029 Protection Manual SEL-411L Relay
Autoreclosing and Synchronism-Check
Two-Circuit-Breaker Autoreclosing
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 for another method to prevent BK2 from becoming the leader.
The following examples help illustrate how the autoreclose logic dynamically
determines the leader and follower circuit breakers. These examples describe
a two circuit breaker scheme (such as used in a circuit breaker-and-a-half
arrangement) as shown in Figure 4.3.
Example One: No Follower
This example describes recloser states when Circuit Breaker BK1 fails to
reclose following the first three-pole open interval delay. Set the FBKCEN
SEL
OGIC control equation to prevent Circuit Breaker BK2 from closing as the
follower. The leader and follower selection settings are shown in Table 4.6.
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 follower
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.
Table 4.5 Dynamic Leader/Follower Settings (Sheet 2 of 2)
SLBK1 SLBK2 FBKCEN Comments
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