Date Code 20170927 Instruction Manual SEL-751 Relay
Appendix D
DNP3 Communications
Overview
The SEL-751 Feeder Protection Relay provides a Distributed Network
Protocol Version 3.0 (DNP3) Level 2 Outstation interface for direct serial and
LAN/WAN network connections to the device.
This section covers the following topics:
➤ Introduction to DNP3 on page D.1
➤ DNP3 in the SEL-751 on page D.6
➤ DNP3 Documentation on page D.14
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 an eight-volume series of specifications. Volume 8 of the specification,
called the Interoperability Specification, simplifies DNP3 implementation by
providing four 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 communications 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 communications requirements
Large RTUs, SCADA
masters
4 Enhanced: additional data types and functionality for
more complex requirements
Large RTUs, SCADA
masters
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