6.146
SEL-421 Relay Instruction Manual Date Code 20171021
Protection Applications Examples
Autoreclose and Synchronism-Check Example
Three-Pole Autoreclose Logic
Set the three-pole open interval time equal to 30 cycles.
3POID1 := 30. Three-Pole Open Interval 1 Delay (1–99999 cycles)
There is no need to enable fast three-pole autoreclose because we have already
used the first and only three-pole shot for this purpose.
3PFARC := NA. Three-Pole Fast ARC Enable (SELOGIC Equation)
Set the reclaim time following a three-pole autoreclose cycle equal to 900 cycles.
3PRCD := 900. Three-Pole Reclaim Time Delay (1–99999 cycles)
Initiate a three-pole autoreclose cycle when the SEL-421 three-pole trips because
of Zone 1 phase-distance protection or a communications-assisted trip. No man-
ual, time-delayed, bus, or circuit breaker failure trips are included in the 3PRI
SEL
OGIC control equation for this application example.
3PRI := 3PT AND (Z1P OR COMPRM). Three-Pole Reclose Initiation
(SEL
OGIC Equation)
You can force the autoreclose logic to skip a three-pole shot. However, it is not
necessary for this application example.
79SKP := NA. Skip Reclosing Shot (SELOGIC Equation)
Only attempt to reclose Circuit Breaker 1 if Bus 1 is hot and the line is dead. The
SEL-421 autoreclose logic only applies this supervision during a three-pole auto-
reclose cycle (you cannot set this setting to NA or logical 0; see Voltage Elements
on page 6.139).
3P1CLS := DLLB1. Three Pole BK 1 Reclose Supervision (SELOGIC Equation)
Only attempt to reclose Circuit Breaker 2 if the synchronism check is successful
or if Circuit Breaker 1 is out of service and the line is dead and Bus 2 is hot. The
SEL-421 autoreclose logic only applies synchronism supervision during a three-
pole autoreclose cycle in this application example (you cannot set this setting to
NA or logical 0).
3P2CLS := 25A2BK2 OR (NOT LEADBK1 AND DLLB2). Three Pole BK 2
Reclose Supervision (SEL
OGIC Equation)
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