6.19
Date Code 20080213
Instruction Manual
SEL-351A Relay
Close and Reclose Logic
Reclosing Relay
These settings are discussed in detail in the remainder of this subsection.
Reclose Initiate and
Reclose Initiate
Supervision Settings
(79RI and 79RIS,
respectively)
The reclose initiate setting 79RI is a rising-edge detect setting. The reclose
initiate supervision setting 79RIS supervises setting 79RI. When setting 79RI
senses a rising edge (logical 0 to logical 1 transition), setting 79RIS has to be
at logical 1 (79RIS = logical 1) in order for open interval timing to be initiated.
If 79RIS = logical 0 when setting 79RI senses a rising edge (logical 0 to
logical 1 transition), the relay goes to the Lockout State.
Factory Settings Example
With factory settings:
79RI =
TRIP
79RIS =
52A + 79CY
the transition of the TRIP Relay Word bit from logical 0 to logical 1 initiates
open interval timing only if the 52A + 79CY Relay Word bit is at logical 1
(52A = logical 1, or 79CY = logical 1). Input
IN101
is assigned as the breaker
status input in the factory settings (52A = IN101).
The circuit breaker has to be closed (circuit breaker status 52A = logical 1) at
the instant of the first trip of the auto-reclose cycle in order for the SEL-351A
to successfully initiate reclosing and start timing on the first open interval. The
SEL-351A is not yet in the reclose cycle state (79CY = logical 0) at the instant
of the first trip.
Then for any subsequent trip operations in the auto-reclose cycle, the
SEL-351A is in the reclose cycle state (79CY = logical 1) and the SEL-351A
successfully initiates reclosing for each trip. Because of factory setting 79RIS
= 52A + 79CY, successful reclose initiation in the reclose cycle state (79CY =
logical 1) is not dependent on the circuit breaker status (52A). This allows
successful reclose initiation for the case of an instantaneous trip, but the
circuit breaker status indication is slow—the instantaneous trip (reclose
initiation) occurs before the SEL-351A sees the circuit breaker close.
If a flashover occurs in a circuit breaker tank during an open interval (circuit
breaker open and the SEL-351A calls for a trip), the SEL-351A goes
immediately to lockout.
Additional Settings Example
The preceding settings example initiates open interval timing on rising edge of
the TRIP Relay Word bit. The following is an example of reclose initiation on
the opening of the circuit breaker.
Presume input
IN101
is connected to a 52a circuit breaker auxiliary contact
(52A = IN101).
79STL
TRIP
Stall Open Interval Timing
79BRS
0
Block Reset Timing
79SEQ
0
Sequence Coordination
79CLS
1
Reclose Supervision
Table 6.4
Reclosing Relay SEL
OGIC
Control Equation Settings
(Sheet 2 of 2)
SEL
OGIC
Control
Equation Setting
Factory Setting
Definition
Summary of Contents for SEL-351A
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