ABB Relion 670 Series Applications Manual page 459

1MRK 505 370-UUS Rev. K
IEC06000519 V2 EN-US
Figure 231: 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 as shown in figure 232. 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 232: 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.
18.1.2.2 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 required optocoupler inputs into every IED it is
Busbar protection REB670
Application manual
Multiplexer
Telecom. Network
*)
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Remote communication
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Multiplexer
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Section 18
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