13.24
SEL-400 Series Relays Instruction Manual Date Code 20171006
SELOGIC Control Equation Programming
SEL
OGIC Control Equation Operators
SELOGIC Control Equation Operators
There are two types of SELOGIC control equations. Boolean SELOGIC control
equations comprise the first type. These equations are expressions that evaluate to
a Boolean value of 0 or 1. Math SEL
OGIC control equations constitute the second
type. The relay evaluates these equations to yield a result having a numerical
value (for example, 6.25 or 1055).
Left value, LVALUE, determines the type of SEL
OGIC control equation you need
for a setting or for writing freeform programming. If the LVALUE is a Boolean
type (ER, ASV001, etc.) then the type of expression you need is a Boolean
SEL
OGIC control equation. If the LVALUE is a numerical (non-Boolean) value
(PMV12, PCT01PV, etc.), the type of expression you need is a math SEL
OGIC
control equation.
Writing SEL
OGIC control equations requires that you use the appropriate opera-
tors and correct SEL
OGIC control equation syntax to combine relay elements
including analog values, Relay Word bits, incoming control points, and SEL
OGIC
control equation elements within the relay. The operators are grouped into two
types, according to the type of SEL
OGIC control equation in which you can apply
these operators.
Operator Precedence
When you combine several operators and operations within a single expression,
the relay evaluates the operations from left to right, starting with the highest pre-
cedence operators working down to the lowest precedence. This means that if
you write an equation with three AND operators, for example PSV01 AND
PSV02 AND PSV03, each AND will be evaluated from the left to the right. If
you substitute NOT PSV04 for PSV03 to make PSV01 AND PSV02 AND NOT
PSV04, the relay evaluates the NOT operation of PSV04 first and uses the result
in subsequent evaluation of the expression. While you cannot use all operators in
any single equation, the overall operator precedence follows that shown in
Table 13.15.
Table 13.15 Operator Precedence From Highest to Lowest (Sheet 1 of 2)
Operator Description
(Expression) Parenthesis
Identifier (argument list) Function evaluation
– Negation
NOT Complement
R_TRIG
F_TRIG Edge Trigger
SQRT, LN, EXP, LOG, COS, SIN, ACOS,
ASIN, ABS, CEIL, FLOOR
Math Functions
* Multiply
/Divide
+Add
– Subtract
<, >, <=, >= Comparison
= Equality
<> Inequality
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