ABB Relion 670 Series Applications Manual page 484

Section 19
Remote communication
IEC06000519 V2 EN-US
Figure 225: 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 converter as shown in figure 226. These solutions
are aimed for connections to a multiplexer, which in turn is connected to a telecommunications
transmission network (for example, SDH or PDH).
*) Converting optical to galvanic G.703
IEC05000527 V2 EN-US
Figure 226: LDCM with an external optical to galvanic converter and a multiplexer
When an external modem G.703 or X21 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.
19.1.3 Setting guidelines
ChannelMode : This parameter can be set Normal or Blocked . Besides this, it can be set
OutOfService which signifies that the local LDCM is out of service. Thus, with this setting, the
communication channel is active and a message is sent to the remote IED that the local IED is out
of service, but there is no COMFAIL signal and the analog and binary values are sent as zero.
478
Multiplexer
Telecom. Network
*)
1MRK 511 358-UUS A
en06000519-2.vsd
Multiplexer
*)
en05000527-2.vsd
Application manual
M12454-3 v5.1.1