Communication Hardware Solutions - ABB REC670 Applications Manual

Section 21
Remote communication
21.1.2.1
568
3-end differential protection with two communication links
IED-A
Ldcm312
IEC16000077 V1 EN-US
Figure 239: Three-end differential protection with two communication links
If the LDCM is in 2Mbit mode, you can send the three local currents as well as the
three remote currents from the other links by configuring the transmitters in IED-B:
1. Ldcm312 transmitter sends the local currents and the three currents received
by Ldcm313.
2. Ldcm313 transmitter sends the three local currents and the three currents
received from Ldcm312.
As a result, six currents are received in IED-A and IED-C. These currents can be
connected to the protection function together with the local three currents.
In order to forward the logic signals (for example, inter-trip or inter-
block) between IED-A and IED-C, the setting LinkForwarded
should be defined. In IED-B, it is set to LDCM313 for Ldcm312
and to LDCM312 for ldcm313.
This setup results in a master-master-master configuration, but without the benefit
of reverting to a slave-master-slave configuration in case of a communication link
interruption. In case of a communication link interruption, all three IEDs would be
blocked.

Communication hardware solutions

The LDCM (Line Data Communication Module) has an optical connection such
that two IEDs can be connected over a direct fibre (multimode), as shown in figure
240. The protocol used is IEEE/ANSI C37.94. The distance with this solution is
typical 110 km.
Ldcm312
IED-B
Ldcm313
1MRK 511 401-UEN A
Ldcm312
IED-C
IEC16000077-1-en.vsd
M12844-11 v5
Bay control REC670 2.2 IEC
Application manual