Date Code 20081022 Instruction Manual SEL-787 Relay
Appendix D
DNP3 Communications
Instructi on Manual
Overview
The SEL-787 Transformer Protection Relay provides a Distributed Network
Protocol Version 3.0 (DNP3) Level 2 Slave interface for direct serial and
LAN/WAN network connections to the device.
This section covers the following topics:
➤ Introduction to DNP3
➤ DNP3 in the SEL-787
➤ DNP3 Documentation, Object Tables, and Data Maps
Introduction to DNP3
A Supervisory Control and Data Acquisition (SCADA) manufacturer
developed the first versions of DNP from the lower layers of IEC 60870-5.
Originally designed for use in telecontrol applications, Version 3.0 of the
protocol has also become popular for local substation data collection. DNP3 is
one of the protocols included in the IEEE
®
Recommended Practice for Data
Communication between Remote Terminal Units (RTUs) and Intelligent
Electronic Devices (IEDs) in a Substation.
The DNP Users Group maintains and publishes DNP3 standards. See the DNP
Users Group website, www.dnp.org, for more information on standards,
implementers, and tools for working with DNP3.
DNP3 Specifications
DNP3 is a feature-rich protocol with many ways to accomplish tasks, defined
in a series of specifications known as the Basic 4. A companion specification
called the Subset Definitions simplifies DNP3 implementation by providing
three standard interoperable implementation levels. The levels are listed in
Table D.1.
Table D.1 DNP3 Implementation Levels
Level Description Equipment Types
1 Simple: limited communication requirements Meters, simple IEDs
2 Moderately complex: monitoring and metering
devices and multifunction devices that contain
more data
Protective relays, RTUs
3 Sophisticated: devices with great amounts of data
or complex communication requirements
Large RTUs, SCADA
masters
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