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7
7.0.1
Fault tracing
Fault tracing
Procedure
1.
Check that the settings are correct.
2.
Check that the optical budget is correct.
3.
COMFAIL occurs for the following reasons:
The COMFAIL signal will be triggered when there is a problem in the communication link be-
tween the two terminals, depending on type of 56/64 modem. Also, normal actions such as a
change of setting, switch off of remote terminal during maintenance etc., can cause COMFAIL.
Comfail function
COMFAIL triggering according to table
COMFAIL
Drop-out delay; t = 200ms
Figure 21:
Comfail triggering.
The 200 ms alarm dropout delay is, for example, required as hysteresis for terminals with reserve
overcurrent, REL 551 or distance reserve function REL 561, if the differential function is
blocked by communication delays and interruptions etc.
The communication failure signal, COMFAIL, depends on the following internal signals (vari-
ables) in each terminal for REx 5xx.
below.
t
en03000125.vsd
Table 10
shows a summary with additional explanations
Chapter 8
Configuring the 56/64 kbit data
communication modules
69
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