ABB Relion 670 Series Applications Manual page 577

1MRK 511 401-UEN Rev. K
IEC06000519 V2 EN-US
Figure 277: Direct fiber optical connection between two IEDs with LDCM
The LDCM can also be used together with an external optical to galvanic G.703 converter or
with an alternative external optical to galvanic X.21 as shown in figure 278. These solutions are
aimed for connections to a multiplexer, which in turn is connected to a telecommunications
transmission network (for example PDH).
*) Converting optical to galvanic G.703
IEC05000527 V2 EN-US
Figure 278: LDCM with an external optical to galvanic converter and a multiplexer
When an external modem G.703 or X.21 is used, the connection between LDCM and the modem
is made with a multimode fiber of max. 3 km length. The IEEE/ANSI C37.94 protocol is always
used between LDCM and the modem.
Alternatively, a LDCM with X.21 built-in converter and micro D-sub 15-pole connector output
can be used.
22.1.3 Setting guidelines
64 kbit mode common settings
ChannelMode defines how an IED discards the LDCM information when one of the IEDs in the
system is out of service: it can either be done on the IED out of service by setting all local
LDCMs to channel mode
LDCM to channel mode
communication to the remote end during the whole maintenance process, that is, no restart or
removal of the fiber can be done.
This setting does not apply to two-end communication.
Bay control REC670
Application manual
Multiplexer
*)
OutOfService or at the remote end by setting the corresponding
Blocked . If OutOfService is selected, the IED should have active
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Telecom. Network
Section 22
Remote communication
en06000519-2.vsd
Multiplexer
*)
en05000527-2.vsd
M12454-3 v9
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