6.14
SEL-400 Series Relays Instruction Manual Date Code 20171006
Autoreclosing
Two-Circuit-Breaker Autoreclosing
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 any of the following occur:
➤ The number of trips exceeds the maximum number of shots (N3PSHOT)
➤ Supervision condition 3PnCLS fails to assert in BKnCLSD time
➤ Relay Word bit 3POLINE asserts for a circuit breaker manual
opening (no qualified autoreclose initiation 3PARC)
➤ The circuit breaker fails to close within BKCFD time
➤ SELOGIC equation 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 sin-
gle-pole trip in the single-pole cycle 79CY1 with a valid SPARC as described in
Single-Pole Mode on page 6.10. The recloser closes the circuit breakers and pro-
ceeds 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 beginning of the three-pole
autoreclose cycle state 79CY3. The recloser proceeds through the 79CY3 state
and exits this state as described in Three-Pole Mode on page 6.12.
Three-Pole Priority
If a single-pole autoreclose cycle is in progress (79CY1) and the relay receives an
initiation for three-pole reclosing (3PRI), the recloser immediately starts a three-
pole autoreclose cycle (79CY3).
Active Circuit Breakers
The following three Relay Word bits describe when Circuit Breaker BK1 and
Circuit Breaker BK2 are active for the autoreclose logic:
➤ NBK0, No Breaker Active in Reclose Scheme
➤ NBK1, One Breaker Active in Reclose Scheme
➤ NBK2, Two Breakers Active in Reclose Scheme
Leader and Follower Circuit Breakers
One circuit breaker is the leader and the other is the follower for circuit breaker-
and-a-half and ring-bus arrangements. Figure 6.2 illustrates a multiple circuit
breaker arrangement. The leader recloses first. If the leader recloses successfully,
the follower also typically recloses.
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