Sel SEL-421 - SPLSHT Deasserted (Single-Pole Shot Remains)

R.2.12
SEL-421 Relay Reference Manual Date Code 20111215
Auto-Reclosing and Synchronism Check
Two-Circuit-Breaker Auto-Reclosing
SPLSHT Deasserted (Single-Pole Shot Remains). The recloser
exhibits four possible state transitions when SPLSHT is not asserted:
➤ If no further trip conditions occur and timer SPRCD expires,
the recloser returns to the reset states BKnRS.
➤ If a single-phase fault occurs while the SPRCD reclaim timer is
timing, then the recloser asserts SPARC if all single-pole
initiate conditions are satisfied and goes to the beginning of the
79CY1 cycle. The recloser then recalculates and freezes the
calculation for 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.
➤ If a multiphase fault occurs during the SPRCD reclaim time,
then the recloser asserts Relay Word bit 3PARC if all three-pole
reclose conditions are satisfied (E3PRn is logical 1, for
example) and recalculates the number of active circuit breakers,
the leader, and the follower before proceeding to the auto-
reclose three-pole cycle state 79CY3.
➤ If a multiphase fault occurs during the SPRCD reclaim time,
SPLSHT is not asserted, and the three-pole reclose conditions
are not satisfied (E3PRn is logical 0, for example) and the
recloser exits the 79CY1 cycle state and goes to the lockout
state BKnLO.
SPLSHT Asserted (Last Shot). The recloser exits the 79CY1 state via
three methods while SPLSHT is asserted:
➤ If no further trip conditions occur and timer SPRCD expires,
the recloser returns to the reset states BKnRS.
➤ If a fault occurs during the SPRCD reclaim time, then the
recloser asserts Relay Word bit 3PARC if all three-pole reclose
conditions are satisfied and proceeds to the auto-reclose three-
pole cycle state 79CY3.
➤ If a fault occurs during the SPRCD reclaim time and the three-
pole reclose conditions are not satisfied (E3PRn is logical 0, for
example), then the recloser exits the 79CY1 cycle state and
goes to the lockout state BknLO.
Lockout State from 79CY1
The recloser goes to lockout (BKnLO) when the number of trips exceeds the
maximum number of shots (NSPSHOT), supervision condition SPnCLS 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.
Three-Pole Mode
Figure 2.14 and Figure 2.15 show the two circuit breaker three-pole auto-
reclose cycle 79CY3 when E79 := Y and E79 := Y1, respectively. The cycle
starts when Relay Word bit 3PARC asserts. The recloser freezes calculation of
the number of breakers, the leader circuit breaker, and the follower circuit
breaker. Depending on the calculation, the recloser asserts the appropriate
Relay Word bits NBK0, NBK1, NBK2, LEADBK0, LEADBK1, LEADBK2,