Schweitzer Engineering Laboratories SEL-351A - Close Logic; Figure 6.1 Close Logic

6.2
SEL-351A Relay Instruction Manual Date Code 20080213
Close and Reclose Logic
Close Logic
Close Logic
The close logic in Figure 6.1 provides flexible circuit breaker closing/
automatic reclosing with SEL
OGIC control equation settings:
52A (breaker status)
CL (close conditions, other than automatic reclosing)
ULCL (unlatch close conditions, other than circuit breaker status, close
failure, or reclose initiation)
and setting:
CFD (Close Failure Time)
See the Settings Sheets in Section 9: Setting the Relay for setting ranges.
q From Figure 6.2.
Figure 6.1 Close Logic
Set Close
If all the following are true:
➤ The unlatch close condition is not asserted (ULCL = logical 0).
➤ The circuit breaker is open (52A = logical 0).
➤ The reclose initiation condition (79RI) is not making a rising-
edge (logical 0 to logical 1) transition.
➤ And a close failure condition does not exist (Relay Word bit
CF = 0).
Then the CLOSE Relay Word bit can be asserted to logical 1 if either of the
following occurs:
➤ A reclosing relay open interval times out (qualified by
SEL
OGIC control equation setting 79CLS—see Figure 6.2).
➤ Or SELOGIC control equation setting CL goes from logical 0 to
logical 1 (rising-edge transition).
52A
Breaker Status
Close Failure
Timer
CF
Rising-Edge Detect
ULCL
CFD = OFF
Reclosing
Relay
Open
Interval
Time-Out
(qualified
by
79CLS)
79RI
52A
Reclose Initiate
Close
Conditions
(other
than
automatic
reclosing)
q
Unlatch Close
(If setting CFD = OFF, the Close
Failure Timer is inoperative
and does not time limit the
CLOSE output condition)
CL
SELOGIC
Settings
CLOSE
Relay
Word
Bits
Pulses (logical 1)
for one processing
interval if Close
Failure Timer
times out (drives
reclosing relay to
lockout)
Close Failure
CFD
0
NOTE: The CLOSE (CC) command is
not embedded in the close logic. It is
included in the factory SEL
OGIC
control equation settings:
CL = … + CC
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