6.16
SEL-400 Series Relays Instruction Manual Date Code 20171006
Autoreclosing
Two-Circuit-Breaker Autoreclosing
Follower Logic
The FBKCEN SELOGIC control equation, Follower Breaker Closing Enable,
defines the conditions necessary for the follower breaker to reclose.
The relay selects the follower as follows:
➤ If Circuit Breaker BK1 is the leader and Circuit Breaker BK2 is not
locked out, then Circuit Breaker BK2 is the follower.
➤ If Circuit Breaker BK2 is the leader and Circuit Breaker BK1 is not
locked out, then Circuit Breaker BK1 is the follower.
➤ If fewer than two circuit breakers are in service (NBK0 or NBK1 is
asserted), then there is no follower.
The following three Relay Word bits describe which circuit breaker is the follower:
➤ FOLBK0, No Follower Breaker
➤ FOLBK1, Follower Breaker = Breaker 1
➤ FOLBK2, Follower Breaker = Breaker 2
If there is no follower (in the case of only one circuit breaker, for example), the
relay loads a logical 0 into the follower SEL
OGIC control equation FBKCEN.
Dynamic Selection of Leader and Follower Circuit Breakers
The relay dynamically selects the leader and follower circuit breakers during the
reclose cycle. The relay calculates the leader in the ready (reset) state. At the start
of the reclose cycle, the relay freezes this calculation and sets circuit breaker des-
ignations. 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 set-
tings SLBK1 (Lead Breaker = Breaker 1), SLBK2 (Lead Breaker = Breaker 2),
and FBKCEN (Follower Breaker Closing Enable). Table 6.5 shows the permuta-
tions of these settings.
Table 6.5 Dynamic Leader/Follower Settings (Sheet 1 of 2)
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 follower upon suc-
cessful 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.
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