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1.15
Date Code 20020501
SEL-2701 Ethernet Processor Instruction Manual
Introduction
UCA2
UCA2
UCA2 is part of the Utility Communications Architecture suite of protocols.
The SEL-2701 provides a UCA2 interface. The following paragraphs describe
UCA2 and UCA2 features in the SEL-2701.
UCA History
The UCA for Field Devices Protocol, now known as UCA2 is the result of an
EPRI (Electric Power Research Institute) joint development effort that began
in the late 1980s. The primary components of UCA are UCA2 and TASE.2
(Telecontrol Application Service Element 2). UCA2 is designed for
communication with substation IEDs. TASE.2, also known as ICCP (Inter-
Control Center Communication Protocol), is designed to move data between
real-time databases.
Both TASE.2 and UCA2 are based on an underlying communication protocol,
MMS (Manufacturing Messaging Specification). MMS is an industrial
automation protocol developed largely by General Motors. General Motors
has long served as a research and development center for advanced
technologies in industrial automation. While MMS is no longer in wide use in
the industrial automation environment, it is a capable protocol that serves as
the foundation for both UCA2 and TASE.2.
UCA2
UCA2 is a profile for object-oriented communication with substation IEDs
using MMS. CASM (Common Application Service Models) defines how
objects interact with MMS services. GOMSFE is the object model
specification for UCA2.
GOMSFE
GOMSFE is an object model for collecting measurement and status data from
substation IEDs. GOMSFE uses an object-oriented abstract to create standard
definitions for presenting meters, protective relays, and other devices on
UCA2 networks. Unlike previous generations of protocols, UCA2 does not
rely on the concept of indices or registers. GOMSFE organizes data into
object models called bricks.
GOMSFE describes multifunction devices with several bricks, each
describing one function. An example of this is a protective relay. A relay may
contain metering data that populate a multiphase metering brick. The
protective relay may also function as a circuit breaker interface with a brick
for a circuit breaker controller.
GOMSFE bricks, consist of pieces of data with standard names built from
standard data types. For example, the polyphase measurement brick (MMXU)
includes A-phase current called MX$A$PhsAf. A-phase current is a value of
the type FLT32 (32-bit floating point), as are the other phase currents.
Standard object models alone do not allow individual manufacturers to
innovate and add new features. Because of this potential limitation, GOMSFE
allows for the extension of bricks and the creation of custom bricks.
Appendix B: UCA2 GOMSFE Models
shows the GOMSFE model bricks
available in the SEL-2701 when it is installed in an SEL-2030. The model
definitions list the SEL-2701 rules for populating the model from data in the
host.
It would be difficult to distribute and update descriptions of GOMSFE models
on every UCA2 network master. A powerful feature of GOMSFE, self-
description, makes extended bricks and custom bricks easy to use and
eliminates the need to store GOMSFE model specification information on
every master. A master UCA2 device can query a slave UCA2 device. The
Summary of Contents for SEL-2701
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