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10-10
Line Current Differential Communications
Date Code 20010625
and Serial Port Communications and Commands
SEL-311L Instruction Manual
Rear Panel TX/RX LED
Each channel interface has two rear-panel LEDs which help in troubleshooting installation
problems. The RX LED illuminates when the channel is enabled and receives valid packets from
another SEL-311L. The RX LED extinguishes if the channel is disabled, if there are sufficient
data errors to prevent the relay from recognizing the packet boundaries, if the receive data is
entirely absent, or, in the case of an EIA-422 port, if the externally supplied RX clock stops.
The TX LED illuminates when the channel is enabled and transmits valid packets. The TX LED
extinguishes if the channel is disabled, or in the case of an EIA-422 interface, if the externally
supplied TX clock stops.
Loopback, End-to-End, and Back-to-Back Testing With the TST Command
The
TST
command temporarily modifies the channel configuration without changing settings.
Upon exiting test mode, the relay reconfigures the channels per the channel settings.
The
TST
command enables short term or long term internal or external loopback tests, end-to-
end tests, or back-to-back tests. To enter the
TST
command, type
TST X
or
TST Y
for Channel
X or Y, respectively. To end the test mode before the duration timer expires, type
TST X C
or
TST Y C
.
After entering the
TST
command, the relay warns that protection and tripping are still enabled.
Cut out the 87L trip contacts to avoid misoperations. This enables you to perform channels tests
while backup protection remains enabled. All applied faults and load current appear as internal
faults when the communications channel is looped back.
All channel monitor functions remain operational during test mode. This allows you to monitor
the channel for errors during the test.
=>>TST X <ENTER>
Entering Test Mode on Channel X.
WARNING!!! Tripping is enabled in test mode. !!!WARNING
Press Ctrl X now to abort. Type "TST X C" to end test mode.
Enable Loop-Back: Internal, External or None (I,E,N) ? E <ENTER>
Timing Source: Internal or External (I,E) ? I <ENTER>
Test Mode Duration: 1 - 30 min. or Infinite (1-30,INF) ? 30 <ENTER>
Are you sure (Y/N) ? Y <ENTER>
Test Mode Enabled on Channel X.
Channel X: Test Mode
Channel Y: Normal Mode
=>>TST C X <ENTER>
Channel X: Normal Mode
Channel Y: Normal Mode
=>>
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