U.5.12
SEL-421 Relay User’s Guide Date Code 20090715
Front-Panel Operations
Front-Panel Layout
If you enter a Relay Word bit or analog quantity that does not match a valid
relay element, the relay displays
Invalid element. If you enter a display
point that exceeds the allowable length, the relay displays:
Too many
characters
. If you enter an invalid scale factor, invalid width, too many
parameters, or omit necessary quotation marks or brackets, the relay displays
an error message. If a display point was used previously and you want to
remove the display point, you can delete the display point. In the Front Panel
settings (SET F), at the Display Points and Aliases prompt, use the text-edit
mode line editing commands to set the display points (see Text-Ed it M ode
Line Editing on page U.4.18 for information on text-edit mode line editing).
To delete Display Point 1, type DELETE <Enter> at the Front Panel settings
Line 1 prompt.
EXAMPLE 5.2 Creating a Display Point
Display points screens provide operator feedback about the
readiness of equipment connected to the SEL-421. A display points
screen contains 11 display points; this example demonstrates a
method to set the display point messages that are shown in
Figure 5.11. The SEL-421 in this example has an additional I/O interface
board.
This example is based on a three-pole circuit breaker, with breaker
input settings entered as shown in Setting a Control Input for Circuit
Breaker Auxiliary Contacts (52A):
ACSELERATOR QuickSet on
page U.4.67. The Relay Word bit 52AA1 will assert when Circuit
Breaker 1 is in the closed position.
IN109 will assert when Circuit Breaker 1 is in an alarm condition.
B2IAFIM is the filtered instantaneous magnitude for the A-Phase
current through Circuit Breaker 2.
In the Front Panel settings (SET F), enter the following after the
Display Points and Aliases line 1 prompt:
1: 1,”Circuit Breaker 1”
2: 52AA1,,“ --Closed--”,“ --Open--”
3: 0
4: 0,”Circuit BK1 SF6 Gas”
5: IN109,,” --Alarm--”,” --Normal--”
6: 1
7: 1,”Circuit Breaker 2”
8: B2IAFIM,” A PH={6.1,1} A pri”
9: IN109,,”SF6 ALARM”, D
Fixed text is set by assigning an alias to a “1” or “0.” Blank lines are
set by assigning a blank alias to a “1” or “0.” The circuit breaker
closed condition is indicated by the set state, “ --Closed--” where
leading spaces are added to center the set state message. Add a
clear state named “ --Open--” to show that the circuit breaker is open.
The circuit breaker alarm condition is indicated by the set state,
“ --Alarm--” where leading spaces are added to center the set state
message. Add a clear state named “ --Normal--” to show that the
circuit breaker is not in alarm. User text “ A PH=” and “A pri” allows
for customized display of the Circuit Breaker 2 A-Phase current,
which has been formatted to display numerically as XXXX.X. Double
font display is used to give greater visibility to the SF6 Alarm. A
horizontal scroll appears while in manual-scrolling mode regardless
of whether or not the display point label width requires two full
screens to display.
Courtesy of NationalSwitchgear.com
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