ABB RET670 Applications Manual page 852

Section 5
Remote communication
846
The protocol used is IEEE/ANSI C37.94. The distance with this solution is typical 110
km/68 miles.
IEC06000519 V2 EN
Figure 326: Direct fibre 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 327. These solutions are aimed for connections to a multiplexer, which in turn is
connected to a telecommunications transmission network (for example, SDH or PDH).
Multiplexer
*) Converting optical to galvanic G.703 or X.21 alternatively
IEC05000527 V1 EN
Figure 327: 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 fibre 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.
Telecom. Network
*)
1MRK504116-UUS C
en06000519-2.vsd
Multiplexer
*)
en05000527.vsd
Application manual