U.5.31
Date Code 20020501
User’s Guide
SEL-421/SEL-421-1 Relay
Front-Panel Operations
Operation and Target LEDs
Operational
The green ENABLED LED indicates that the relay is active. Trip events
illuminate the TRIP LED. The prominent location of the red TRIP LED in the
top target area helps you recognize a trip event quickly.
TARGET RESET and Lamp Test
For a trip event, the relay latches the trip-involved target LEDs (except for the
ENABLED LED and the Recloser Status area LEDs). Press the TARGET
RESET pushbutton to reset the latched target LEDs. When a new trip event
occurs and you have not reset the previously latched trip targets, the relay
clears the latched targets and displays the new trip targets.
Pressing the TARGET RESET pushbutton illuminates all the LEDs. Upon
releasing the TARGET RESET pushbutton, two possible trip situations can
exist: the conditions that caused the relay to trip have cleared or the trip
conditions remain present at the relay inputs. If the trip conditions have
cleared, the latched target LEDs turn off. If the trip event conditions remain,
the relay re-illuminates the corresponding target LEDs. The TARGET RESET
pushbutton also removes the trip automatic message displayed on the LCD
menu screens if the trip conditions have cleared.
Lamp Test Function With TARGET RESET
The TARGET RESET pushbutton also provides a front-panel lamp test.
Pressing TARGET RESET illuminates all the front-panel LEDs, and these
LEDs remain illuminated for as long as you press TARGET RESET. The
target LEDs return to a normal operational state after you release the
TARGET RESET pushbutton.
Lamp Test Function With LCD DISPLAY TEST Menu
The LCD menus provide a front-panel DISPLAY TEST mode. This menu-
activated lamp test, from the DISPLAY TEST menu, does not reset the target
LEDs (see
Other Target Reset Options
You can reset the target LEDs with the ASCII command
TAR R
; see
on page R.8.48 in the Reference Manual
for more information. You can reset
the targets from the
AC
SEL
ERATOR
software Control branch of the HMI tree
view. Programming specific conditions in the SEL
OGIC
control equation
RSTTRGT is another method to reset the relay targets. Access RSTTRGT in
the relay Global settings (Data Reset Control); to use RSTTRGT, you must
enable data reset control with global setting EDRSTC := Y.
Trip Type
The SEL-421 Relay indicates essential information about the most recent
relay trip event with the LEDs of the Trip Type area. These trip types are
INST, TIME, COMM, and SOTF. For information on setting the
corresponding trip logic, see
Trip Logic on page R.1.103 in the Reference
The INST target LED illuminates, indicating operation of the SEL-421 Relay
instantaneous elements. This LED lights if elements M1P (the Zone 1 mho
phase distance element) or Z1G (the Zone 1 mho ground distance element)
pick up and the relay has not illuminated the COMM or SOTF targets.
The TIME target LED indicates that a timed relay element caused a relay trip.
lists the elements that activate the TIME LED in the factory default
settings.
Summary of Contents for SEL-421
Page 8: ...This page intentionally left blank ...
Page 30: ...This page intentionally left blank ...
Page 110: ...This page intentionally left blank ...
Page 204: ...This page intentionally left blank ...
Page 284: ...This page intentionally left blank ...