6.21
Date Code 20080213 Instruction Manual SEL-351A Relay
Close and Reclose Logic
Reclosing Relay
4. If the following setting is made:
79RIS = 0 (numeral 0)
reclosing will never take place (the reclosing relay goes directly
to the lockout state any time reclosing is initiated). The
reclosing relay is effectively inoperative.
Drive-to-Lockout and
Drive-to-Last Shot
Settings (79DTL and
79DLS, respectively)
When 79DTL = logical 1, the reclosing relay goes to the Lockout State (Relay
Word bit 79LO = logical 1), and the front-panel LO (Lockout) LED
illuminates.
79DTL has a 60-cycle dropout time. This keeps the drive-to-lockout condition
up 60 more cycles after 79DTL has reverted back to 79DTL = logical 0. This
is useful for situations where both of the following are true:
➤ Any of the trip and drive-to-lockout conditions are “pulsed”
conditions (e.g., the OPEN command Relay Word bit, OC,
asserts for only 1/4 cycle—refer to the following Factory
Settings Example).
➤ Reclose initiation is by the breaker contact opening (e.g.,
79RI = !52A—refer to Additional Settings Example on
page 6.19).
Then the drive-to-lockout condition overlaps reclose initiation and the
SEL-351A stays in lockout after the breaker trips open.
When 79DLS = logical 1, the reclosing relay goes to the last shot, if the shot
counter is not at a shot value greater than or equal to the calculated last shot
(see Reclosing Relay Shot Counter on page 6.18).
Factory Settings Example
The drive-to-lockout factory setting is:
79DTL = !IN102 + LB3 + OC
Optoisolated input IN102 is set to operate as a reclose enable switch (see
Optoisolated Inputs on page 7.2). When Relay Word bit IN102 = logical 1
(reclosing enabled), the relay is not driven to the Lockout State (assuming
local bit LB3 = logical 0, too):
!IN102 = !(logical 1) = NOT(logical 1) = logical 0
79DTL = !IN102 + LB3 + OC = (logical 0) + LB3 = LB3 + OC
When Relay Word bit IN102 = logical 0 (reclosing disabled), the relay is
driven to the Lockout State:
!IN102 = !(logical 0) = NOT(logical 0) = logical 1
79DTL = !IN102 + LB3 + OC = (logical 1) + LB3 + OC = logical 1
Local bit LB3 is set to operate as a manual trip switch (see Local Control
Switches (Only on Models With LCD) on page 7.5 and Trip Logic on
page 5.1). When Relay Word bit LB3 = logical 0 (no manual trip), the relay is
not driven to the Lockout State (assuming optoisolated input IN102 = logical
1, too):
79DTL = !IN102 + LB3 + OC = NOT(IN102) + (logical 0) + OC
= NOT(IN102) + OC
When Relay Word bit LB3 = logical 1 (manual trip), the relay is driven to the
Lockout State:
79DTL = !IN102 + LB3 + OC = NOT(IN102) + (logical 1) + OC = logical 1
NOTE: On models with no LCD, local
control bits LB1–LB16 are permanently
logical 0 and LB3 will have no effect
on setting 79DTL (factory settings).
Courtesy of NationalSwitchgear.com
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