4.164
SEL-751 Relay Instruction Manual Date Code 20170927
Protection and Logic Functions
Logic Settings (SET L Command)
Figure 4.96 Result of Falling-Edge Operator on a Deasserting Input
You can use the falling-edge operator with the NOT operator as long as the
NOT operator precedes the F_TRIG operator. The NOT F_TRIG combination
produces a logical 0 for one processing interval when it detects a falling edge
on the specified element.
Math Arithmetic Operators (*, /, +, and –)
If you use Relay Word bits (which are effectively Boolean resultants, equal to
logical 1 or logical 0) in mathematical operations, the relay treats these as
numerical values 0 and 1, depending on whether the Relay Word bit is equal to
logical 0 or logical 1, respectively.
Boolean Comparison Operators (<, >, <=, and >=)
Comparisons are mathematical operations that compare two numerical values,
with the result being a logical 0 (if the comparison is not true) or logical 1 (if
the comparison is true). Thus, what starts out as a mathematical comparison
ends up as a Boolean resultant. For example, if the output of a math variable is
greater than a certain value, an output contact is asserted:
OUT103 := MV01 > 8
If the math variable (MV01) is greater than 8 in value, output contact OUT103
asserts (OUT103 = logical 1). If the math variable (MV01) is less than or
equal to 8 in value, output contact OUT103 deasserts (OUT103 = logical 0).
Boolean Equality (=) and Inequality (<>) Operators
Equality and inequality operators operate similar to the comparison operators.
These are mathematical operations that compare two numerical values, with
the result being a logical 0 (if the comparison is not true), or logical 1 (if the
comparison is true). Thus, what starts out as a mathematical comparison, ends
up as a Boolean resultant. For example, if the output of a math variable is not
equal to a certain value, an output contact is asserted:
OUT102 := MV01 <> 45
If the math variable (MV01) is not equal to 45 in value, output contact
OUT102 asserts (effectively OUT102 := logical 1). If the math variable
(MV01) is equal to 45 in value, output contact OUT102 deasserts (effectively
OUT102 := logical 0). Table 4.61 shows other operators and values that you
can use in writing SEL
OGIC control equations.
F_TRIG IN101
IN101
Falling Edge
One Processing Interval
One Processin
Interval
To Next Page
Loading...
