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 BK
n
RS.
➤
If a fault occurs during the 3PRCD reclaim time and 3PLSHT is
asserted, then the recloser goes to lockout BK
n
LO.
Lockout State From 79CY3
The recloser goes to lockout (BK
n
LO) when any of the following occur:
➤
The number of trips exceeds the maximum number of shots (N3PSHOT)
➤
Supervision condition 3P
n
CLS fails to assert in BK
n
CLSD 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
➤
SEL
OGIC
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
. 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 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.
illustrates a multiple circuit
breaker arrangement. The leader recloses first. If the leader recloses successfully,
the follower also typically recloses.
Summary of Contents for SEL-421-4
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