4.75
Date Code 20081022 Instruction Manual SEL-787 Relay
Protection and Logic Functions
Logic Settings (SET L Command)
The executed result of a math SELOGIC control equation is stored in a math
variable. The smallest and largest values a math variable can represent are
–16777215.99 and +16777215.99, respectively. If the executed result exceeds
these limits, it will be clipped at the limit value. For example, when the
MV01:= executed result is –16777219.00, MV01 will be –16777215.99.
Similarly, when the MV02 := executed result is +16777238.00, MV02 will be
+16777215.99.
Comments can be added to both boolean and math SEL
OGIC control equations
by inserting a # symbol. Everything following the # symbol in a SEL
OGIC
control equation is treated as a comment. See Table 4.28 for this and other
Boolean and math operators and values.
Operator Precedence
When you combine several operators and operands within a single expression,
the SEL-787 evaluates the operators from left to right, starting with the
highest precedence operators and working down to the lowest precedence.
This means that if you write an equation with three AND operators, for
example SV01 AND SV02 AND SV03, each AND will be evaluated from the
left to the right. If you substitute NOT SV04 for SV03 to make SV01 AND
SV02 AND NOT SV04, the device evaluates the NOT operation of SV04 first
and uses the result in subsequent evaluation of the expression.
Parentheses Operator ( )
You can use more than one set of parentheses in a SELOGIC control equation
setting. For example, the following Boolean SEL
OGIC control equation setting
has two sets of parentheses:
SV04 := (SV04 OR IN102) AND (PB01_LED OR RB01)
In the above example, the logic within the parentheses is processed first and
then the two parentheses resultants are ANDed together. Use up to 14 sets of
parentheses in a single SEL
OGIC control equation setting. The parentheses
cannot be “nested” (parentheses within parentheses).
Ta b le 4. 27 S E LOGIC Control Equation Operators (Listed in Operator
Precedence)
Operator Function
Function Type (Boolean
and/or Mathematical)
( ) parentheses Boolean and Mathematical
(highest precedence)
– negation Mathematical
NOT NOT Boolean
R_TRIG rising-edge trigger/detect Boolean
F_TRIG falling-edge trigger/detect Boolean
*
/
multiply
divide
Mathematical
Mathematical
+
-
add
subtract
Mathematical
Mathematical
<, >, <=, >= comparison Boolean
=
<>
equality
inequality
Boolean
Boolean
AND AND Boolean
OR OR Boolean (lowest
precedence)
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