R.2.14
SEL-421 Relay Reference Manual Date Code 20111215
Auto-Reclosing and Synchronism Check
Two-Circuit-Breaker Auto-Reclosing
follower close command, the recloser starts timer BKCFD (Breaker Close
Failure Delay). If the follower fails to close, the recloser sends the follower to
lockout after timer BKCFD expires. If the leader circuit breaker is not in
lockout, the recloser begins timing 3PRCD reclaim time for the leader.
If the follower breaker closes successfully, the recloser starts the 3PRCD
(Three-Pole Reclaim Time Delay) timer if 79BRCT (Block Reclaim Timer) is
not asserted.
3PRCD Reclaim Timing
The recloser determines subsequent state transitions during reclaim timing
according to the status of Relay Word bit 3PLSHT (Three-Pole Reclose Last
Shot).
3PLSHT Deasserted (Three-Pole Shot Remains)
The recloser exhibits two possible state transitions when 3PLSHT is not
asserted:
➤ If no further trip conditions occur and timer 3PRCD expires,
the recloser returns to the reset states BKnRS.
➤ If a fault occurs while the 3PRCD reclaim timer is timing, then
the recloser asserts 3PARC if all three-pole initiate conditions
are satisfied and goes to the beginning of the 79CY3 cycle. The
recloser then recalculates and freezes the number of active
circuit breakers, the leader, and the follower. The recloser then
increments the shot counter and begins the next open interval
timer.
3PLSHT Asserted (Last Shot)
The recloser exits the 79CY3 state via two methods while 3PLSHT is
asserted:
➤ If no further trip conditions occur and timer 3PRCD expires,
the recloser returns to the reset states BKnRS.
➤ If a fault occurs during the 3PRCD reclaim time and 3PLSHT
is asserted, then the recloser goes to lockout BKnLO.
Lockout State from 79CY3
The recloser goes to lockout (BKnLO) when the number of trips exceeds the
maximum number of shots (N3PSHOT), supervision condition 3PnCLS fails
to assert in BK1CLSD time, Relay Word bit 3POLINE asserts (for a circuit
breaker manual opening), the circuit breaker fails to close within BKCFD
time, or any time Relay Word bit 79DTL asserts.
Single- and Three-Pole Mode
The single- and three-pole mode (SPAR/3PAR) uses elements of both the
single-pole mode (SPAR) and the three-pole mode (3PAR). Reclosing begins
after a single-pole trip in the single-pole cycle 79CY1 with a valid SPARC as
described in Single-Pole Mode on page R.2.11. The recloser closes the circuit
breakers and proceeds to the reclaim timer SPRCD. If a fault occurs during the
SPRCD reclaim time and SPLSHT is asserted, then the recloser asserts Relay
Word bit 3PARC if all three-pole reclose conditions are satisfied. Upon
asserting 3PARC, the recloser exits the 79CY1 cycle state and goes to the
To Next Page
Loading...
