ABB REC670 Applications Manual page 604

Section 21
Remote communication
598
ChannelMode defines how an IED discards the LDCM information when one of the
IEDs in the system is out of service: it can either be done on the IED out of service by
setting all local LDCMs to channel mode OutOfService or at the remote end by setting
the corresponding LDCM to channel mode Blocked. If OutOfService is selected, the
IED should have active communication to the remote end during the whole
maintenance process, that is, no restart or removal of the fibre can be done.
This setting does not apply to two-end communication.
Blocked
OutOfService
TerminalNo is used to assign a unique address to each LDCM in all current differential
IEDs. Up to 256 LDCMs can be assigned a unique number. For example, in a local
IED with two LDCMs:
• LDCM for slot 305: set TerminalNo to 1 and RemoteTermNo to 2
• LDCM for slot 306: set TerminalNo to 3 and RemoteTermNo to 4
In multiterminal current differential applications,with 4 LDCMs in each IED, up to 20
unique addresses must be set.
A unique address is necessary to give high security against incorrect
addressing in the communication system. If the same number is used
for TerminalNo in some of the LDCMs, a loop-back test in the
communication system can give an incorrect trip.
RemoteTermNo is used to assign a number to each related LDCM in the remote IED.
For each LDCM, RemoteTermNo is set to a different value than TerminalNo, but equal
to the TerminalNo of the remote end LDCM. In the remote IED, TerminalNo and
RemoteTermNo are reversed as follows:
• LDCM for slot 305: set TerminalNo to 2 and RemoteTermNo to 1
• LDCM for slot 306: set TerminalNo to 4 and RemoteTermNo to 3
The redundant channel is always configured to the lower position, for
example:
• Slot 305: main channel
• Slot 306: redundant channel
IED does not use data from the LDCM
IED informs the remote end that it is out of service
1MRK 511 401-UUS A
Bay control REC670 2.2 ANSI
Application manual