Sel SEL-421 - Single-Pole Mode; SPRCD Reclaim Timing

R.2.5
Date Code 20111215 Reference Manual SEL-421 Relay
Auto-Reclosing and Synchronism Check
One-Circuit-Breaker Auto-Reclosing
Relay Word bit 3PARC asserts when all necessary conditions to begin a three-
pole auto-reclose cycle are satisfied (E3PR1, for example) and the recloser
receives a three-pole reclose initiation 3PRI (see Figure 2.9).
Other recloser settings include the initial recloser settings (see Enable Auto-
Reclose Logic for Two Circuit Breakers on page R.2.23) and the trip logic
enable settings E3PT, E3PT1, and E3PT2. When SEL
OGIC control equations
E3PT, E3PT1, and E3PT2 are deasserted, a single-pole reclose follows a
single-pole trip; when these SEL
OGIC control equations are asserted, only
three-pole tripping and reclosing result (see Trip Logic and Reclose Sources
on page R.2.9).
Single-Pole Mode
Figure 2.10 shows the one circuit breaker single-pole auto-reclose cycle
79CY1. The cycle starts when Relay Word bit SPARC asserts. The recloser
waits as long as 10 cycles for the circuit breaker to open (indicated by Relay
Word bit SPO) and then begins timing SPOID (Single-Pole Open Interval
Delay) when the circuit breaker opens. If the circuit breaker does not open
within 10 cycles, the recloser goes to the lockout state. After single-pole open
interval time SPOID expires, the relay recloses the circuit breaker if
supervisory condition SP1CLS (Single-Pole BK1 Reclose Supervision) is
satisfied within the duration of timer BK1CLSD (BK1 Reclose Supervision
Delay).
At the reclose command, the recloser starts timer BKCFD (Breaker Close
Failure Delay). If the circuit breaker fails to close, the recloser goes to lockout
(BK1LO) after timer BKCFD expires.
SPRCD Reclaim Timing
If the circuit breaker closes, the recloser starts timer SPRCD (Single-Pole
Reclaim Time Delay). The recloser determines subsequent state transitions
during reclaim timing according to the status of Relay Word bit SPLSHT
(Single-Pole Reclose Last Shot). When SPLSHT is asserted, the recloser
forces all subsequent relay trips to three-pole only mode.
SPLSHT Asserted (Last Shot). The recloser exits the 79CY1 state via three
methods while SPLSHT is asserted:
➤ If no further trip conditions occur, the recloser goes to the reset
state BK1RS after reclaim timer SPRCD expires.
➤ 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 (E3PR1 is logical 0, for
example) the recloser exits the 79CY1 cycle state and goes to
the lockout state BK1LO.