ABB RELION 670 Series Applications Manual page 400

Section 17
Remote communication
IEC06000519 V2 EN-US
Figure 191: 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 192. 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 192: 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.
17.1.2.2 Application possibility with one-phase REB670
For busbar protection applications in substations where dynamic zone selection is required, it is
typically necessary to wire the normally open and normally closed auxiliary contacts from every
monitored disconnector and/or circuit breaker to the optocoupler inputs of the busbar
protection. When one phase version of REB670 is used, then six optocoupler inputs (that is, two in
each phase/IED) are required for every primary switchgear object. For big stations (for example,
with 24 bays) this will require quite a lot of binary inputs into every IED. To limit the number of
394
Multiplexer
Telecom. Network
*)
1MRK 505 337-UUS A
en06000519-2.vsd
Multiplexer
*)
en05000527-2.vsd
Application manual
M12844-20 v4