Schweitzer Engineering Laboratories SEL-311L, Instruction Manual, Page: 281 / 734

Date Code 20010625 Inputs, Outputs, Timers, and Other Control Logic 7-29
SEL-311L Instruction Manual
Note: Make Active Setting Group Switching Settings with Care
The active setting group is stored in nonvolatile memory so it can be retained during power loss
or settings change. The nonvolatile memory is rated for a finite number of “writes” for all
setting group changes. Exceeding the limit can result in an EEPROM self-test failure. An
average of 10 setting groups changes per day can be made for a 25-year relay service life.
This requires that SEL
OGIC
control equation settings SS1 through SS6 (see Table 7.4) be set with
care. Settings SS1 through SS6 cannot result in continuous cyclical changing of the active
setting group. Time setting TGR qualifies settings SS1 through SS6 before changing the active
setting group. If optoisolated inputs IN101 through IN106 are used in settings SS1 through SS6,
the inputs have their own built-in debounce timer that can help in providing the necessary time
qualification (see Figure 7.1).
SEL
OGIC
C
ONTROL
E
QUATION
V
ARIABLES
/T
IMERS
Sixteen (16) SEL
OGIC
control equation variables/timers are available. Each SEL
OGIC
control
equation variable/timer has a SEL
OGIC
control equation setting input and variable/timer outputs
as shown in Figure 7.23 and Figure 7.24.
Timers SV1T through SV6T in Figure 7.23 have a setting range of a little over 4.5 hours:
0.00–999999.00 cycles in 0.25-cycle increments
Timers SV7T through SV16T in Figure 7.24 have a setting range of almost 4.5 minutes:
0.00–16000.00 cycles in 0.25-cycle increments
These timer setting ranges apply to both pickup and dropout times (SV n PU and SV n DO,
n = 1 through 16).
Figure 7.23: SEL
OGIC
Control Equation Variables/Timers SV1/SV1T Through SV6/SV6T