Schweitzer Engineering Laboratories SEL-421-4, Instruction Manual

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6.5
Date Code 20171006 Instruction Manual SEL-400 Series Relays
Autoreclosing
One-Circuit-Breaker Autoreclosing
Other recloser settings include the initial recloser settings (see Enable Autore-
close Logic for Two Circuit Breakers on page 6.22 ) and the trip logic enable set-
tings 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 for Single-Pole Breaker
Applications on page 6.9 ).
Single-Pole Mode
NOTE:
Single-pole mode is only
supported in relays that provide
single-pole breaker control.
Figure 6.11 shows the one circuit breaker single-pole autoreclose 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 cir-
cuit breaker opens. 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 subse-
quent relay trips to three-pole only mode.
SPLSHT Asserted (Last Shot)
The recloser exits the 79CY1 state via one of the following 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 autoreclose 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.
SPLSHT Deasserted (Single-Pole Shot Remains)
The recloser exhibits four possible state transitions when SPLSHT is not asserted:
➤
If no further trip conditions occur, the recloser goes to the reset state
BK1RS after timer SPRCD expires.
➤
If a single-phase fault occurs while the SPRCD reclaim timer is
timing, the recloser asserts SPARC for single-pole initiate conditions
and returns to the beginning of the 79CY1 cycle state; the recloser
increments the shot counter and begins the next open interval timer.