Hitachi Relion 670 Series Applications Manual page 395

1MRK506375-UEN Rev. N
IEC06000519 V2 EN-US
Figure 197:
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 198. 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 198:
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.
19.1.3 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 OutOfService or at the remote end by setting the corresponding LDCM to channel
mode Blocked. If OutOfService is selected, the IED should have active 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.
Blocked
Railway application RER670
Application manual
Direct fiber optical connection between two IEDs with LDCM
Multiplexer
*)
LDCM with an external optical to galvanic converter and a multiplexer
IED does not use data from the LDCM
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Telecom. Network
Section 19
Remote communication
en06000519-2.vsd
Multiplexer
*)
en05000527-2.vsd
M12454-3 v10
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