Date Code 20001006 Close and Reclose Logic 6-17
SEL-351 Instruction Manual
Thus, open interval times 79OI3 and 79OI4 are not operable. In the factory settings, both open
interval times 79OI3 and 79OI4 are set to zero. But if the settings were:
79OI3 = 0.00 cycles
79OI4 = 900.00 cycles (set to some value other than zero)
open interval time 79OI4 would still be inoperative, because a preceding open interval time is set to
zero (i.e., 79OI3 = 0.00).
If open interval 1 time setting, 79OI1, is set to zero (79OI1 = 0.00 cycles), no open interval timing
takes place, and the reclosing relay is defeated.
The open interval timers time consecutively; they do not have the same beginning time reference
point. In the above factory settings, open interval 1 time setting, 79OI1, times first. If the
subsequent first reclosure is not successful, then open interval 2 time setting, 79OI2, starts timing.
If the subsequent second reclosure is not successful, the relay goes to the Lockout State. See the
example time line in Figure 6.6.
Figure 6.6: Reclosing Sequence From Reset to Lockout With Factory Settings
SELOGIC Control Equation setting 79STL (stall open interval timing) can be set to control open
interval timing [see Skip Shot and Stall Open Interval Timing Settings (79SKP and 79STL,
respectively) later in this subsection].
Determination of Number of Reclosures (Last Shot)
The number of reclosures is equal to the number of open interval time settings that precede the first
open interval time setting set equal to zero. The “last shot” value is also equal to the number of
reclosures.
In the above factory settings, two set open interval times precede open interval 3 time, which is set
to zero (79OI3 = 0.00):
79OI1 = 30.00
79OI2 = 600.00
79OI3 = 0.00
For this example:
Number of reclosures (last shot) = 2 = the number of set open interval times that precede the
first open interval set to zero.
Courtesy of NationalSwitchgear.com
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