ABB Relion 670 Series Applications Manual page 315

1MRK 511 407-UUS Rev. J
IEC06000519 V2 EN-US
Figure 117: 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 as shown
in figure 118. 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 118: LDCM with an external optical to galvanic converter and a multiplexer
When an external modem G.703 is used, the connection between LDCM and the modem is made
with a multimode fiber of max. 3 km/2 mile length. The IEEE/ANSI C37.94 protocol is always used
between LDCM and the modem.
20.1.3 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
channel mode
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.
Phasor measurement unit RES670
Application manual
Multiplexer
*)
OutOfService or at the remote end by setting the corresponding LDCM to
Blocked . If OutOfService is selected, the IED should have active communication to
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Telecom. Network
Remote communication
en06000519-2.vsd
Multiplexer
*)
en05000527-2.vsd
Section 20
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