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13.34
SEL-400 Series Relays
Instruction Manual
Date Code 20171006
SEL
OGIC
Control Equation Programming
Effective Programming
FLOOR
Use the FLOOR operator to round the argument to the nearest integer toward
minus infinity. Use parentheses to group a math expression as the argument of a
FLOOR operation.
contains examples of the FLOOR operator.
Negation
Use the negation (–) operation to change the sign of the argument. The argument
of the negation operation is multiplied by –1. Negation of a positive value results
in a negative value, while negation of a negative value results in a positive value.
contains examples of expressions that utilize the negation operator.
Effective Programming
This section contains several ideas useful for creating, maintaining, and trouble-
shooting programming in SEL-400 series relays protection and automation
SEL
OGIC
control equation programming environments.
Planning and Documentation
When you begin to configure the relay to perform a new automation task or cus-
tomize protection operation, take time to design, document, and implement your
project. Scale the planning effort to match the overall size of the project, but
spend sufficient time planning to do the following:
➤
Document the inputs and outputs of your programming. This may
include protection elements, physical inputs and outputs, metering
quantities, user inputs, and other information within the relay.
➤
Document the processing or outcome of the programming. List the
major tasks you want the relay to perform and provide detail about
the algorithm you will use for each task. For example, if you need a
timer or a counter, make a note of the requirements and how you will
use these elements.
Example 13.20
Using the FLOOR Operator
The freeform math SEL
OGIC
control equations below show examples of the
FLOOR operator usage.
# FLOOR examples
AMV001 :=
FLOOR (5.99)
# Stores 5 in AMV001
AMV002 :=
FLOOR (–4.01)
# Stores –5 in AMV002
Example 13.21
Using the Negation Operator
The freeform math SEL
OGIC
control equations below show examples of
negation operator usage.
# Negation examples
AMV001 :=
-AMV009
# If AMV009 is 5, stores –5 in AMV001
AMV002 :=
-AMV009
# If AMV009 is –5, stores 5 in AMV002
Summary of Contents for SEL-421-4
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