Schweitzer Engineering Laboratories SEL-311L, Instruction Manual, Page: 241 / 734

Date Code 20010625 Close and Reclose Logic 6-23
SEL-311L Instruction Manual
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).
After successful reclose initiation, open interval timing does not start until allowed by the stall
open interval timing setting 79STL. If 79STL = logical 1, open interval timing is stalled. If
79STL = logical 0, open interval timing can proceed.
If an open interval time has not yet started timing (79STL = logical 1 still), the 79SKP setting is
still processed. In such conditions (open interval timing has not yet started timing), if 79SKP =
logical 1, 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 turns out to be 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).
If the relay is in the middle of timing on an open interval and 79STL changes state to 79STL =
logical 1, open interval timing stops where it is. If 79STL changes state back to 79STL = logical
0, open interval timing resumes where it left off. Use the OPTMN Relay Word bit to monitor
open interval timing (see
Monitoring Open Interval and Reset Timing earlier in this
subsection).
Settings Example
The skip shot function is not enabled in the example settings:
79SKP = 0 (numeral 0)
The stall open interval timing setting is:
79STL = TRIP + TRIP87