ABB RED650 Applications Manual

sending, information on real phase currents from the two local CTs will not be
available at the remote line end.
In 64 kbit mode, the decision on using one communication channel instead of two
(as show in Figure
35) must be made case by case. Correct information on bias
currents is always available locally while only distorted information is available at
the end that receives limited information using only one LDCM.
6.1.2.6 Configuration of analog signals
M12022-86 v5
Currents from the local end enter the IED as analog values via the Analog input
modules. These currents are converted to digital values and then forwarded to the
line differential protection function in the local IED. From there, they are
transmitted to remote IEDs via a Line differential communication module
(LDCM). Currents coming from a remote IED are received as digital values via
local IED's LDCM, and they are then forwarded to the protection function in the
local IED.
LDLPSCH acts as the interface to and from the protection function.
Configuration of this data flow is made in the SMT tool as shown in Figure
36.
Currents from
remote end 1
Currents to
remote end 1
Currents from
remote end 2
Currents to
remote end 2
LDCM 2
LDCM 1
Currents from
local CT
A/D
SMAI
Pre-processing
block
Line Differential
function
L3DPDIF
IEC05000533-2-en.vsd
IEC05000533-NEW V2 EN-US
Figure 36: Typical configuration of analog signals for a three-terminal line
Figure 36 shows how one IED in a three-terminal line differential protection can be
configured. There are two LDCMs each supporting a duplex connection with a
remote line end. Thus, the same local current is configured to both LDCMs, while
the received currents from the LDCMs are configured separately to the line
differential protection function.
Section 6 1MRK 505 393-UEN B
Differential protection
84 Line differential protection RED650 2.2 IEC
Application manual

ABB RED650 Specifications

General

Brand	ABB
Model	RED650
Category	Protection Device
Language	English