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6-20
Close and Reclose Logic
Date Code 20011205
SEL-311B Instruction Manual
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.
Settings Example
With 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-311B to successfully initiate reclosing and
start timing on the first open interval. The SEL-311B 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-311B is in the reclose
cycle state (79CY = logical 1) and the SEL-311B successfully initiates reclosing for each trip.
Because of 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-311B sees the circuit
breaker close.
If a flashover occurs in a circuit breaker tank during an open interval (circuit breaker open and
the SEL-311B calls for a trip), the SEL-311B 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).
With setting:
79RI =
!52A
the transition of the 52A Relay Word bit from logical 1 to logical 0 (breaker opening) initiates
open interval timing. Setting 79RI looks for a logical 0 to logical 1 transition, thus Relay Word
bit 52A is inverted in the 79RI setting [!52A = NOT(52A)].
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