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4.10
SEL-421 Relay
Instruction Manual
Date Code 20171021
Front-Panel Operations
Target LEDs
shows the arrangement of the operation and target LEDs region into
several areas described in
.
Trip Type
The SEL-421 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
.
The
INST
target LED illuminates, indicating operation of the SEL-421 instanta-
neous elements. This LED lights if elements Z1P (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 set-
tings.
Figure 4.9
Factory-Default Front-Panel Target Areas (16 or 24 LEDs)
Table 4.2
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
, BKR FAIL
, LOP
Miscellaneous Status
PMCU OK
, IRIG LOCKED
Synchrophasor Status
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19)
(20)
(21)
(22)
(23)
(24)
Summary of Contents for SEL-421-4
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