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 fromLdcm312.As a result, six currents are received in IED-A and IED-C. These currents can be connected tothe 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 settingLinkForwarded should be defined. In IED-B, it is set toLDCM313 for Ldcm312 and toLDCM312 for ldcm313.This setup results in a master-master-master configuration, but without the benefit ofreverting to a slave-master-slave configuration in case of a communication link interruption. Incase of a communication link interruption, all three IEDs would be blocked.4.6 Configurations with power transformers in theprotected zone4.6.1 Line differential protection L3CPDIF, L6CPDIF, LT3CPDIF,LT6CPDIF4.6.1.1 Power transformers in the protected zone M12541-6 v7One three-winding transformer or two two-winding transformers can be included in the lineprotection zone. The alternative with one two-winding transformer in the protected zone isshown in Figure 25 and Figure 26.IED IEDProtected zoneIEC05000442-2-en.vsdxIEC05000442 V2 EN-USFigure 25: One two–winding transformer in the protected zoneSection 4 1MRK 505 382-UEN EAnalog and binary signal transfer for line differential protection28 Communication set-up, 670/650 seriesApplication Guide© Copyright 2017 ABB. All rights reserved
