ABB Relion 670 series - VPN (Virtual Private Network)

5.6.3 Detecting communication faults on transceiver 21-219
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Some LED indicators on the transceiver 21–219 front panel can be used for
communication fault tracing as shown in Table
Table 30: LED indicators used for detecting communication faults
LED name Fault indication
LA Local Alarm. Red LED indicates that transceiver 21-219 has detected a fault
condition in the C37.94 protocol (LOS = Loss Of Signal). The Yellow Alarm bit is
set in the outgoing C37.94 protocol.
The red LED is lit when transceiver 21-219 has detected an error. The indication
has a memory function. When the local error is no longer present, the LED blinks
until the Reset button is pressed.
RA
Remote Alarm. Red LED indicates that the remote unit has detected a fault
condition, and has set the Yellow Alarm bit in the C37.94 protocol.
The red LED is lit when the fibre-optic link has detected an error. The indication has
a memory function. When the remote error is no longer present, the LED blinks
until the Reset button is pressed.
If the line differential protection IED shows a communication fail alarm but LA or
RA LED is not lit on transceiver 21-219, communication interruption stems from
the telecommunication network.
5.6.4 Detecting communication faults through loop-back testing
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Loop-back tests are an efficient way to trace the origin of communication faults.
Loop-back testing means that loop-backs are created to the local line differential
protection IEDs at different points in the communication network. Testing
encompasses both fibre-optic and galvanic cable loop-backs depending on their
actual positions in the communication network (see Figure
83).
Loop-back testing with X.21 galvanic interface requires special
procedures and equipment. Contact your local ABB representative
for more details.
Procedure:
1. Block the trip circuits.
2. Set the local and remote terminals to have the same address (TerminalNo and
RemoteTermNo) on the local HMI under Main menu/Configuration/
Communication/LDCM communication.
3. Select the synchronization method (GPS or echo).
In most cases, the synchronization method used in loop-back
testing should be the same as is used in actual service.
However, in some test cases, for example with only a single
1MRK 505 382-UEN B Section 5
Communication set-up
Communication set-up 670/650 series 2.2 99
Application Guide