Date Code 20011026 Specifications 2-23
SEL-321/321-1 Instruction Manual
SELOGIC Control Equation Operator Order of Operations
When the SEL
OGIC control equations are computed, the ! is applied first, followed by AND (*)
functions, and finally OR (+) functions are computed. The *, +, and ! functions may be used in
any combination for any output contact. For example, to signal that the relay tripped by a
switch-onto-fault operation, program one of the output contacts as follows (OUT 4 shown as an
example):
OUT4 = TPA * SOTFE + TPB * SOTFE + TPC * SOTFE
This logic says that if TPA, TPB, or TPC assert while SOTFE is asserted, that OUT4 asserts to
indicate a SOTF operation.
Exceptions
1. Variables (V, W, X, Y, or Z) cannot be programmed to themselves.
2. SEL
OGIC control equation variables can only be programmed with elements defined before
them in the element list. Within Table 2.10, before means those elements to the right of the
one being programmed.
3. Table 2.5 lists combinations of SEL
OGIC control equation operators that are not acceptable:
Table 2.5: Unacceptable SEL
OGIC Control Equation Operator Combinations
*+ ** !* !+
+* ++ !!
Program any single internal-use element from Table 2.12 to an output contact as long as nothing
else is programmed to that output.
Programming an output equation to NA disables that output contact.
Relay Elements
Table 2.6 through Table 2.15 show the set of relay elements. For the SEL-321-1, use Table 2.6
through Table 2.9 and Table 2.16 through Table 2.24. Display any row of relay elements using
the TARGET command and the TAR numbers in the left column of each table.
Table 2.6 shows front-panel status indicators. These are not logic elements. They correspond to
the front-panel targets and bear the front-panel target names.
Table 2.6: Front-Panel Status Indicators
TAR Status Indicators
0
INST TIME COMM SOTF ZONE1 ZONE2 ZONE3 ZONE4
1
EN A B C G Q 51 50
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