ABB Relion Series 670 Manual page 36

Section 3
Substation Configuration description Language (SCL)
30
supported services. The structure of the IED section follows the definitions made in
the IEC 61850 standard.
Two basic IED types are used in system configuration.
• Station level IEDs
are located on the station level and are identified as client IEDs when they read or
write information from or to the bay IEDs. This functionality is represented by
logical nodes of group "Information (I)". These are the logical nodes (LN) =
ITCI, IHMI and ITMI. Client IEDs are the receiver of information in monitoring
direction and sender of commands (control). These logical nodes have no data
objects. They are only used to link the report control blocks (BRCBs) from the
server IEDs. They have to read their information about the signals and the signal
configuration from the bay IEDs. This is possible by checking all control blocks
for a link to it as a client.
• Bay level IEDs
are located on the bay level and are identified as server IEDs when they read or
write information vertically. When GOOSE messages are received, the bay level
IED also has the client role.
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