ABB RER670 Applications Manual page 462

Section 19
Remote communication
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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
The same is applicable for slot 312-313 and slot 322-323.
DiffSync defines the method of time synchronization for the line differential
function: Echo or GPS.
IED does not use data from the LDCM
IED informs the remote end that it is out of service
1MRK 506 375-UEN A
Railway application RER670 2.2 IEC
Application manual