R.2.13
Date Code 20111215 Reference Manual SEL-421 Relay
Auto-Reclosing and Synchronism Check
Two-Circuit-Breaker Auto-Reclosing
FOLBK0, FOLBK1, and FOLBK2. The recloser checks SELOGIC control
equation 79SKP at this point to determine whether to increment the shot
counter.
The recloser waits for 3POLINE to assert:
➤ if E79 := Y, 3POLINE asserts when both breakers (leader and
follower) open (see Figure 2.6)
➤ if E79 := Y1, 3POLINE asserts when at least one breaker
(leader or follower) opens (see Figure 2.7)
If 3POLINE asserts, the recloser proceeds to timing 3POID1 (Three-Pole
Open Interval 1 Delay). In applications where 3POLINE may not reliably
assert while in the 79CY3 state, we recommend forcing the auto-reclose cycle
into a drive-to-lockout state (79DTL = 1) after a fixed time delay. You can do
this by using the entry into the cycle state (79CY3 = 1) as an input to a
conditioning timer. The conditioning timer applies a pickup delay, and the
relay 79DTL setting includes the conditioning timer output. The time delay
should be long enough to allow normal breaker operation to occur, while
preventing the auto-reclose logic from stalling while waiting indefinitely for
3POLINE to assert. If SEL
OGIC control equation 3PFARC (Three-Pole Fast
ARC Enable) is asserted, the recloser times the open interval time from setting
3PFOID (Three-Pole Fast Open Interval Delay). When E79 := Y1, a Three-
Pole Open Interval Supervision Condition (3POISC) must be satisfied before
the recloser can proceed to timing 3POID1. If the supervisory condition is not
met within the duration of timer 3POISD (Three-Pole Open Interval
Supervision Delay), the recloser goes to lockout.
After three-pole open interval time 3POID or 3PFOID expires
➤ and E79 := Y, the recloser attempts to close the leader breaker,
as discussed below (first checking the supervisory condition
3PnCLS)
➤ and E79 := Y1, the recloser checks if the leader breaker is open.
If open, it attempts to close the leader breaker, as discussed
below (first checking the supervisory condition 3PnCLS). If the
leader breaker is closed (it never opened at the outset), the
recloser skips the leader breaker close logic and attempts to
close the follower breaker, as discussed further below (first
checking for two active breakers and an open follower breaker,
before starting timer TBBKD [Time Between Breakers for
ARC])
The recloser closes the leader if supervisory condition 3PnCLS (Three-Pole
BKn Reclose Supervision) is satisfied within the duration of timer BKnCLSD
(BKn Reclose Supervision Delay).
At the leader close command, the recloser starts timer BKCFD (Breaker
Close Failure Delay). If the leader fails to close, the recloser sends the leader
to lockout BKnLO after timer BKCFD expires. If the leader closes within the
BKCFD time, the recloser goes to 3PRCD (Three-Pole Reclaim Time Delay)
reclaim timing if NBK1 is asserted, or prepares to close the follower circuit
breaker if NBK2 is asserted.
To close the follower circuit breaker, the recloser checks for two active circuit
breakers in the scheme. If NBK2 is asserted, the recloser checks for a three-
pole open on the follower and starts timer TBBKD (Time Between Breakers
For ARC). When TBBKD expires, the recloser closes the follower breaker if
FBKCEN (Follower Breaker Closing Enable) is asserted and supervisory
condition 3PnCLS is satisfied within the duration of timer BKnCLSD. At the
To Next Page
Loading...
