7.26
SEL-351A Relay Instruction Manual Date Code 20080213
Inputs, Outputs, Timers, and Other Control Logic
Multiple Setting Groups
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 1 setting group
change per day can be made for a 25-year relay service life.
This requires that SEL
OGIC control equation settings SS1–SS6 (see Table 7.4)
be set with care. Settings SS1–SS6 cannot result in continuous cyclical
changing of the active setting group. Time setting TGR qualifies settings SS1–
SS6 before changing the active setting group. If optoisolated inputs IN101–
IN106 are used in settings SS1–SS6, the inputs have their own built-in
debounce timer that can help in providing the necessary time qualification (see
Figure 7.1).
Courtesy of NationalSwitchgear.com
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