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2.0.2
60
Fault tracing
Table 4:
Summary
No.
COMFAIL triggering
1
Transmit error
2
Receive error
3
Block differential protection
4
Remote terminal COMFAIL
5
Time synchronization error
6
Differential clock drift
7
Communication channel loop
delay - instantaneous
8
Communication channel loop
delay - time delayed
9
Abnormal clock deviation
10
Data flow
Only in version *2.3
Explanation of contents in column 2 of table 42
1. Transmit errors are due to that the terminal cannot send messages via the tele-
communication channel (PCM). The line differential function initiates the send-
ing of one message every 5 ms. If this command can not be executed for 10
consecutive times (= 10 x 5 ms) due to blocked, missing or unsynchronized com-
munication channel, COMFAIL is triggered. For non-consecutive interruptions,
an integration algorithm is used that prolongs the COMFAIL triggering time.
2. Receive errors occur when no expected messages are received. The line differen-
tial function expects to receive one message every 5 ms. If this does not occur 10
consecutive times (= 10x5 ms), COMFAIL is triggered. For non-consecutive in-
terruptions, an integration algorithm is used that prolongs the COMFAIL trigger-
ing time.
Configuring the 56/64 kbit data
COMFAIL trigger-
Remark
ing time
(Drop-out delay
200 ms)
≥ 50 ms
Messages can not be sent
≥ 100 ms
No valid messages received
0 ms
Block of the differential protection due to set-
ting changes etc.
0 ms
COMFAIL from the remote terminal. For error
no 1, 2, 3, and no 5, 6, 7, 8, 9, 10 the COM-
FAIL is sent in the second consecutive mes-
sage (within 10 ms)
≥ 2 s
Problems in the synchronization of internal
differential clock in the differential protection.
The clock refers to the synchronized counters
0-39999 μ s in each terminal. The clock is
independent of the real time clock in the ter-
minal.
> 0 ms
Unacceptable drift of the internal differential
clock in the slave terminal compared to the
internal differential clock in the master termi-
nal (slave- master -slave)
0 ms
Checks if the loop time (slave - master -slave)
in the differential communication channel 31
ms
≥ 2 s
Checks if the loop time (local - remote- local)
in the differential communication channel 24
ms
0 ms
Internal differential clock deviation (slave-
master - slave)
0 ms
Long time between attempts to send mes-
sages and adjustment of the real time termi-
nal clock . The terminal clock is the real time
clock in the terminal for time tagging of events
etc.
Chapter 8
communication modules
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