U.5.37
Date Code 20090715 User’s Guide SEL-421 Relay
Front-Panel Operations
Operation and Target LEDs
Operational
The ENABLED LED indicates that the relay is active. Trip events illuminate the
TRIP LED. The prominent location of the TRIP LED in the top target area helps
you recognize a trip event quickly. Program settings EN_LEDc and TR_LEDc
to determine the color of the respective LED. Options include red or green.
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 Display Test on page U.5.33).
Other Target Reset Options
You can reset the target LEDs with the ASCII command TAR R; see TARGET
on page R.9.50 for more information.
Table 5.11 Front-Panel Target LEDs
Label Function
ENABLED, TRIP
Operational
INST, TIME, COMM, SOTF
Trip Type
ZONE 1, ZONE 2, ZONE 3, ZONE 4
Zone Activated
PHASE A, PHASE B, PHASE C, GROUND
Phase(s) or Ground
50, 51
Instantaneous and Time-Delayed Overcurrent
79 RESET, 79 LOCKOUT, 79 CYCLE
a
a
Only available in 24 LED models..
Recloser Status
25 SYNCH
a
, BKR CLOSE
a
, BKR FAIL
a
,
OSB
a
, LOP
a
Miscellaneous Status
PMCU OK
a
, IRIG LOCKED
a
Synchrophasor Status
Courtesy of NationalSwitchgear.com
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