Communication Between Channels Via Line Data Communication Module; Configuration Of Analog Signals - Hitachi 670 Series Application Manual

Section 4
Analog and binary signal transfer for line differential protection
In 64 kbit mode, the decision on using one communication channel instead of two (as show in Figure
14) 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.
In 2 Mbit mode, it is possible to send up to 9 different analog signals from each LDCM; therefore only
one LDCM can be used.
4.2 Communication between channels via Line data
communication module
Communication between two IEDs requires that each IED is equipped with a Line Data
Communication Module (LCDM). The LDCM then acts as an interface to 64 kbit/s and 2Mbit/s
communication channels for duplex communication between the IEDs.
IEC10000229 V2 EN-US
Figure 15:
4.3

Configuration of analog signals

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 16.
22
Selection of LDCM for analog or binary signal transfer
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Communication set-up, 670/650 series
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