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4-8
Control Logic
Date Code 20020129
SEL-387E Instruction Manual
If settings are changed (for the active setting group or one of the other setting groups), the active
setting group is retained.
If settings are changed for a setting group other than the active setting group, no interruption of
the active setting group occurs (the relay is not momentarily disabled).
If the settings change causes a change in one or more SEL
OGIC
control equation settings SS1
through SS6, the active setting group can be changed, subject to the newly enabled SS1 through
SS6 settings.
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 through SS6 be set with some 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.
SEL
OGIC
C
ONTROL
E
QUATION
S
ETS
(1
THROUGH
3) V
ARIABLES
Each Setting Group (1 through 6) has three sets of SEL
OGIC
control equation variables for use in
constructing control equations. In the SEL-387E these variables are of two types: timed
variables and latch bits. The variables are processed in the order in which they appear in the
Settings Sheets. If variables that appear earlier are used as inputs to later variables, the
processing of both will occur within the same processing interval. If a later variable is an input
to an earlier variable, the scheme output will be delayed one processing interval.
The SEL
OGIC
control equation sets must be enabled by Group settings ESLS1, ESLS2, and/or
ESLS3, in the configuration settings.
There are a total of 16 timed variables and 16 latch bits available to the user. The three SEL
OGIC
control equation sets have different mixes of variable types, as shown below in Table 4.4.
Table 4.4: SEL
OGIC
Control Equation Variable Mix by Set
SEL
OGIC
Control
Equation Set
Timed Variables
Latch Bits
1 4 4
2 4 4
3 8 8
Содержание SEL-387E
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