6.144
SEL-421 Relay Instruction Manual Date Code 20171021
Protection Applications Examples
Autoreclose and Synchronism-Check Example
Recloser Closing
Select one shot of single-pole autoreclose.
NSPSHOT := 1. Number of Single-Pole Reclosures (N, 1, 2)
Use an external switch to select when the leader or follower circuit breaker is
enabled for single-pole autoreclose.
ESPR1 := IN205. Single-Pole Reclose Enable—BK1 (SELOGIC Equation)
ESPR2 := IN206. Single-Pole Reclose Enable—BK2 (SELOGIC Equation)
Select one shot of three-pole autoreclose.
N3PSHOT := 1. Number of Three-Pole Reclosures (N, 1–4)
Use an external switch to select when the leader or follower circuit breaker is
enabled for three-pole autoreclose.
E3PR1 := IN207. Three-Pole Reclose Enable—BK1 (SELOGIC Equation)
E3PR2 := IN208. Three-Pole Reclose Enable—BK2 (SELOGIC Equation)
The time delay before Circuit Breaker 2 attempts a reclose after Circuit Breaker 1
has successfully reclosed is 15 cycles. The short delay prevents both circuit
breakers closing back into a permanent fault.
TBBKD := 15. Time Between Breakers for ARC (1–99999 cycles)
If either circuit breaker fails to close within 10 seconds after the reclose com-
mand is received, the autoreclose logic goes to lockout for the failed circuit
breaker.
BKCFD := 600. Breaker Close Failure Delay (OFF, 1–99999 cycles)
You can use a normally-closed (a) auxiliary contact from the Circuit Breaker 1
disconnect switch to denote that this circuit breaker is the leader when in service.
Use the contact to energize a control input; if the disconnect switch is closed, the
input is energized.
SLBK1 := IN107. Lead Breaker = Breaker 1 (SELOGIC Equation)
We have selected Circuit Breaker 1 as the leader. The autoreclose logic automati-
cally recognizes Circuit Breaker 2 as the leader when Circuit Breaker 1 is out of
service.
SLBK2 := 0. Lead Breaker = Breaker 2 (SELOGIC Equation)
Circuit Breaker 2 is the follower circuit breaker. The follower can attempt to
reclose if all three poles of Circuit Breaker 2 are actually open or if Circuit
Breaker 1 is out of service.
FBKCEN := 3POBK2 OR (NOT LEADBK1). Follower Breaker Closing Enable
(SEL
OGIC Equation)
Unlatch the reclose command to Circuit Breaker 1 when all three poles are
closed.
ULCL1 := 52AA1 AND 52AB1 AND 52AC1. Unlatch Closing for Breaker 1
(SEL
OGIC Equation)
Unlatch the reclose command to Circuit Breaker 2 when all three poles are closed.
ULCL2 := 52AA2 AND 52AB2 AND 52AC2. Unlatch Closing for Breaker 2
(SEL
OGIC Equation)
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