4.162
SEL-751 Relay Instruction Manual Date Code 20170927
Protection and Logic Functions
Logic Settings (SET L Command)
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 previous 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 paren-
theses 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).
An example of a single Relay Word bit is as follows:
SV01 := NOT RB01
Ta b le 4 . 6 0 S ELOGIC 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
+
-
add
subtract
Mathematical
<, >, <=, >= comparison Boolean
=
<>
equality
inequality
Boolean
AND AND Boolean
OR OR Boolean (lowest precedence)
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