H-4 IEC 61850 Communications Date Code 20080110
SEL-387E Instruction Manual
IEC 61850 devices are capable of self-description. You do not need to refer to the specifications
for the logical nodes, measurements, and other components to request data from another IEC
61850 device. IEC 61850 clients can request and display a list and description of the data
available in an IEC 61850 server device. This process is similar to the autoconfiguration process
used within SEL communications processors (SEL-2032 and SEL-2030). Simply run an MMS
browser to query devices on an IEC 61850 network and discover what data are available. Self-
description also permits extensions to both standard and custom data models. Instead of having
to look up data in a profile stored in its database, an IEC 61850 client can simply query and
IEC 61850 device and receive a description of all logical devices, logical nodes, and available
data.
Unlike other Supervisory Control and Data Acquisition (SCADA) protocols that present data as a
list of addresses or indices, IEC 61850 presents data with descriptors in a composite notation
made up of components.
Table H.2 shows how the A-phase current expressed as
MMXU$A$phsA$cVal is broken down into its component parts.
Table H.2: Example IEC 61850 Descriptor Components
Components Description
MMXU Logical Node Polyphase measurement unit
A Data Object Phase-to-ground amperes
PhsA Sub-Data Object Phase A
cVal Data Attribute Complex value
Data Mapping
Device data is mapped to IEC 61850 Logical Nodes (LN) according to rules defined by SEL.
Refer to IEC 61850-5:2003(E) and IEC 61850-7-4:2003(E) for the mandatory content and usage
of these LNs. The SEL-387E Logical Nodes are grouped under Logical Devices for organization
based on function. See
Table H.3 for descriptions of the Logical Devices in an SEL-387E. See
Logical Nodes for a description of the LNs that make up these Logical Devices.
Table H.3: SEL-387E Logical Devices
Logical Device Description
ANN Annunciator elements – alarms, status values
CFG Configuration elements – datasets and report control blocks
CON Control elements – Remote bits
MET Metering or Measurement elements – currents, voltages, power, etc.
PRO Protection elements – protection functions and breaker control
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