Figure 23: Switchgear With Sensor Measurement And Process Bus Application Of Voltage Sharing And Synchrocheck - ABB UniGear Series Engineering Manual

Process interfaces to MV apparatus (for example voltage sensors) are on the process level.
Besides the conventional signal wiring between the process interface and protection relays,
IEC 61850 introduces a concept where process signals can be exchanged in process bus, un-
der IEC 61850-9-2. In MV switchgear application the station and the process bus can be com-
bined to one common bus. When using conventional voltage instrument transformers (VTs)
in MV switchgear they are usually located in the incoming feeders on the cable side and the
busbar voltage is measured in any of the outgoing feeders or in dedicated metering panel.
The sharing of the busbar voltage is done by interconnection wires between busbar VTs and
protection relays in all outgoing feeders. Usage of sensors and IEC 61850-9-2 has significant
effect on the design of the switchgear. The signal from the voltage sensor measuring the
busbar voltage in one of the protection relay is digitized into sampled values stream shared
over Ethernet network. The interconnection wiring in switchgear becomes simplified as less
regular galvanic signal wires are needed. Transmitting voltage signal over process bus enable
also higher error detection because the signal transmission is supervised.
Figure 23: Switchgear with sensor measurement and process bus application of voltage
sharing and synchrocheck
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