ABB Relion 670 Series Applications Manual page 555

1MRK 511 401-UUS F
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 248: 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/2 mile 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.
21.1.3 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.
Blocked
OutOfService
TerminalNo is used to assign a unique address to each LDCM in all current differential IEDs. Up to
256 LDCMs can be assigned a unique number. For example, in a local IED with two LDCMs:
Bay control REC670
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
IED does not use data from the LDCM
IED informs the remote end that it is out of service
© Copyright 2017 ABB. All rights reserved
Telecom. Network
Remote communication
Multiplexer
*)
en05000527-2.vsd
Section 21
M12454-3 v8
549