4.74
SEL-787 Relay Instruction Manual Date Code 20150130
Protection and Logic Functions
Logic Settings (SET L Command)
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 as many as
14 sets of parentheses in a single SEL
OGIC control equation setting. The
parentheses can be “nested” (parentheses within parentheses).
Math Negation Operator (–)
The negation operator – changes the sign of a numerical value. For example:
MV01 := RB01
When Remote bit RB01 asserts, Math variable MV01 has a value of 1, i.e.,
MV01 = 1. We can change the sign on MV01 with the following expression:
MV01 := –1 * RB01
Now, when Remote bit RB01 asserts, Math variable MV01 has a value of –1,
i.e., MV01 = –1.
Boolean NOT Operator (NOT)
Apply the NOT operator to a single Relay Word bit and to multiple elements
(within parentheses).
Table 4 . 29 SELOGIC 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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