6.17
Date Code 20171006 Instruction Manual SEL-400 Series Relays
Autoreclosing
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 lock-
out 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 6.17 for
another method to prevent BK2 from becoming the leader.
The following examples help illustrate how the relay autoreclose logic dynami-
cally 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 6.3.
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 6.6.
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 suc-
cessful close of the leader BK1.
110Same as 1/0/0.
111Same as 1/0/1.
1 0 52AA1 BK1 is the leader; BK2 to LO is the leader if BK1 LO.
BK2 will close as the follower after TBBKD upon success-
ful close of the leader BK1.
Table 6.5 Dynamic Leader/Follower Settings (Sheet 2 of 2)
SLBK1 SLBK2 FBKCEN Comments
Figure 6.3 Multiple Circuit Breaker Arrangement
Bus 1
(Leader) (Follower)
Line
Three-phase fault
Bus 2
BK2
BK1
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