R.3.8
SEL-421 Relay Reference Manual Date Code 20111215
SELOGIC Control Equation Programming
Multiple Setting Groups
NOTE: Perform operations that are
not time critical in automation
SEL
OGIC control equation
programming. You can use this
automation to reduce the demand and
complexity of protection SEL
OGIC
control equation programming.
All of the SELOGIC control equation programming in the protection area
executes at the same deterministic interval as the protection algorithms.
Because of this type of programming execution, you can use protection free-
form and fixed programming to extend and customize protection operation.
Automation
Automation SELOGIC control equation programming is a large free-form
programming area that consists of 10 blocks. The relay executes each block
sequentially from the first block to the last. You do not need to fill a block
completely or enter any equations in a block before starting to write SEL
OGIC
control equations in the following blocks.
The SEL-421 dedicates a minimum processing time when executing
automation SEL
OGIC control equations. If the processing load is light, the
relay uses more processing time for executing programming. This means that
the overall execution time fluctuates. You can display the average and peak
execution time with the STATUS S ASCII command. Use the STATUS SC
command to reset the peak execution time.
NOTE: Organize automation SELOGIC
control equation programming into
blocks based on function. It is easier
to edit and troubleshoot small
partially filled blocks that contain
related programming.
Use automation SELOGIC control equation programming to automate tasks
that do not require time-critical, deterministic execution. For example, if you
are coordinating control inputs from a substation HMI and SCADA master,
use automation free-form SEL
OGIC control equations and set the output
contact setting to the automation SEL
OGIC control equation variable that
contains the result.
Perform time-critical tasks with protection free-form SEL
OGIC control
equations. For example, if you require a SEL
OGIC control equation for TR
(trip) that contains more than 15 elements, you must perform that calculation
in several steps. Because detection of a TR condition is a time-critical activity,
perform the calculation with protection free-form SEL
OGIC control equations
and set TR to the protection SEL
OGIC control equation variable that contains
the result.
Outputs
To provide protection and automation area separation, the output settings are
in a fixed SEL
OGIC control equation area separate from protection and
automation programming. You can take advantage of this separation to
combine protection and automation in a manner that best fits your application.
Outputs include the relay control outputs, outgoing M
IRRORED BITS
®
points,
and communications card control points. The relay executes output logic and
processes outputs at the protection processing interval.
Multiple Setting Groups
The SEL-421 has six (6) independent setting groups, as shown in the left-hand
side of Figure 3.2. Each setting group has complete relay settings (distance,
directional, overcurrent, reclosing, etc.—see SHO on page R.9.44) and
protection SEL
OGIC settings (see SHO L on page R.9.46). The active setting
group can be:
➤ Shown or selected with the SEL ASCII serial port GROUP
command—see GROUP on page R.9.22.
➤ Shown or selected with the MAIN menu Set/Show menu item
and the
Active Group submenu item as described in
Figure 5.34 on page U.5.31.
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