6-24
Close and Reclose Logic
Date Code 20001006
SEL-351 Instruction Manual
Additional Settings Example 1
The preceding drive-to-lockout factory settings example drives the relay to the Lockout State
immediately when the reclose enable switch (optoisolated input IN2) is put in the “reclosing
disabled” position (Relay Word bit IN2 = logical 0):
79DTL
= !IN2 + ... = NOT(IN2) + ... = NOT(logical 0) + ... = logical 1
To disable reclosing, but not drive the relay to the Lockout State until the relay trips, make settings
similar to the following:
79DTL
= !IN2 * TRIP + ...
Additional Settings Example 2
To drive the relay to the Lockout State for fault current above a certain level when tripping (e.g.,
level of phase instantaneous overcurrent element 50P3), make settings similar to the following:
79DTL
= TRIP * 50P3 + ...
Additionally, if the reclosing relay should go to the Lockout State for an underfrequency trip, make
settings similar to the following:
79DTL
= TRIP * 81D1T + ...
Other Settings Considerations
If no special drive-to-lockout or drive-to-last shot conditions are desired, make the following
settings:
79DTL
= 0
(numeral 0)
79DLS
= 0
(numeral 0)
With settings 79DTL and 79DLS inoperative, the relay still goes to the Lockout State (and to last
shot) if an entire automatic reclose sequence is unsuccessful.
Overall, settings 79DTL or 79DLS are needed to take the relay to the Lockout State (or to last
shot) for immediate circumstances.
Skip Shot and Stall Open Interval Timing Settings (79SKP and 79STL, Respectively)
The skip shot setting 79SKP causes a reclose shot to be skipped. Thus, an open interval time is
skipped, and the next open interval time is used instead.
If 79SKP = logical 1 at the instant of successful reclose initiation (see preceding discussion on
settings 79RI and 79RIS), the relay increments the shot counter to the next shot and then loads the
open interval time corresponding to the new shot (see Table 6.3). If the new shot is the “last shot,”
no open interval timing takes place, and the relay goes to the Lockout State if the circuit breaker is
open (see
Lockout State
earlier in this subsection).
Summary of Contents for SEL-351
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