R.3.4
SEL-421 Relay Reference Manual Date Code 20111215
SELOGIC Control Equation Programming
SELOGIC Control Equation Programming
SELOGIC Control Equation Programming
There are two major areas where the SEL-421 uses SELOGIC control
equations. First, fixed SEL
OGIC control equations define the operation of fixed
protection elements or outputs. As with SEL-300 series relay programming,
protection programming and outputs use fixed SEL
OGIC control equations.
Second, you can use free-form SEL
OGIC control equations for free-form
programming that includes mathematical operations, custom logic execution
order, extended relay customization, and automated operation.
Fixed SELOGIC Control
Equations
Fixed result SELOGIC control equations are equations in which the left side
(result storage location), or LVALUE, is fixed. Programming in SEL-300
series relays consists of all fixed SEL
OGIC control equations. Fixed equations
include protection and output settings that you set with SEL
OGIC control
equations.
SEL-421 fixed SEL
OGIC control equations are Boolean equations. Fixed result
control equations can be as simple as a single element reference (for example
PSV01) or can include a complex equation. An example of fixed
programming is shown in Example 3.1.
EXAMPLE 3.1 Fixed SELOGIC Control Equations
The following equations are examples of fixed SEL
OGIC control
equations for relay Output OUT101. The text after the # character is a
comment included in the equation and stored in the relay for future
reference and documentation.
OUT101 := 1 # Turn on OUT101
OUT101 := NA # Do not evaluate an equation for OUT101
OUT101 := OUT102 AND RB02 # Turn on OUT101 if OUT102 and RB02 are on
Fixed SELOGIC control equations include expressions that evaluate to
a Boolean value, True or False, represented by a logical 1 or logical 0.
OUT101 := PSV04 # Turn on OUT101 if protection PSV04 is on
More complex programming in the free-form area controls OUT101.
The result of the free-form programming is available as an element in
a fixed equation.
OUT101 := AMV003 > 5 # Turn on OUT101 if AMV003 is greater than 5
While you cannot perform mathematical operations in fixed
programming, you can perform comparisons on the results of
mathematical operations performed elsewhere.
Free-Form SELOGIC
Control Equations
Free-form SELOGIC control equations provide advanced relay customization
and automation programming. There are free-form SEL
OGIC control equation
programming areas used for protection and automation. You can use free-form
SEL
OGIC control equation programming to enter program steps sequentially
so that the relay will perform steps in the order that you specify. You can refer
to storage locations multiple times and build up intermediate results in
successive equations. You can also enter entire line comments to help
document programming. Mathematical operations are available only in free-
form SEL
OGIC control equation programming areas. An example of free-form
SEL
OGIC control equation programming is shown in Example 3.2.
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