8.14
SEL-751 Relay Instruction Manual Date Code 20170927
Front-Panel Operations
Two-Line Display Front Panel
Settings T0n_LED are SELOGIC control equations that work with the
corresponding T0nLEDL latch settings to illuminate the LEDs shown in
Figure 8.25. Use settings T0nLEDC to select the LED color (R–red, G–green,
A–amber). Parameter n is a number from 1 through 6 that indicates each LED.
If the latch setting (T0nLEDL) for a certain LED is set to N, then the LED
follows the status of the corresponding control equation (T0n_LED). When
the equation asserts, the LED illuminates, and when the equation deasserts,
the LED extinguishes. If the latch setting is set to Y, the LED only asserts if a
trip condition occurs and the T0n_LED equation is asserted at the time of the
trip. At this point, the LED latches in. You can reset this LED by using the
TARGET RESET pushbutton or the TAR R command, as long as the target
conditions are absent. For a concise listing of the default programming on the
front-panel LEDs, see Table 4.98.
The SEL-751 comes with slide-in labels for custom LED designations that
match custom LED logic. The Configurable Label kit (includes blank labels,
word processor templates, and instructions) is provided when the SEL-751 is
ordered.
The ENABLED LED indicates that the relay is powered correctly, is functional,
and has no self-test failures. Trip events illuminate the TRIP LED. The
prominent location of the TRIP LED in the top target area aids in recognizing
trip events quickly.
The TRIP LED has an additional function that notifies you of warning
conditions. When the TRIP LED is flashing, the warning conditions in
Table 8.3 are active when you set the corresponding relay element. For Relay
Word bit definitions, see Appendix K: Relay Word Bits.
TARGET RESET Pushbutton
Target Reset
For a trip event, the SEL-751 latches the trip-involved target LEDs except for
the ENABLED LED. Press the TARGET RESET pushbutton to reset the latched target
LEDs. When a new trip event occurs and the previously latched trip targets
have not been reset, the relay clears the latched targets and displays the new
trip targets. Pressing and holding the TARGET RESET pushbutton illuminates all
the LEDs. Upon release of 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
Table 8.3 Possible Warning Conditions (Flashing TRIP LED)
Warning Message Relay Word Bit Logic Condition
Arc Flash Status Warning AFALARM
Power Factor Warning 55A
RTD Warning WDGALRM+BRGALRM+AMBALRM+OTHALRM
RTD Failure RTDFLT
Comm Loss Warning COMMLOSS
Comm Idle Warning COMMIDLE
NOTE: The target LEDs are restored
to their previous state after the relay
is turned off and then turned back
on.
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