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The UCA Evaluation Kit CD ROM provides you with the world's first and only package that comes with everything included for the fastest possible start to learn about UCA/MMS/IEC61850

Is IEC 61850 competing with UCA 2.0? No! IEC 61850 is the solution - UCA is the brand name. Read the new two page comparison (2004-08-31; updated 2004-09-13)

The Utility Communications Architecture (UCA) was developed under the sponsorship of the Electric Power Research Institute (EPRI) through a process of broad industry involvement. The objective has been to allow for seamless integration across the utility enterprise using off-the-shelf international standards to reduce costs. UCA Version 2.0 has been published as IEEE technical report TR1550 in November 1999.

IEC 61850 and IEC 61850 based standards:

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UCA differs from most previous utility protocols in its use of object models of devices and device components. These models define common data formats, identifiers, and controls for substation and feeder devices such as measurement unit (see figure 1), switches, voltage regulators, and relays. The models specify standardized behavior for the most common device functions, and allow for significant vendor specialization to allow for future innovation. The models have been developed through an open process including broad vendor and utility participation. These standardized models allow for multivendor interoperability and ease of integration. Modern protocols (such as those found in UCA) make use of the reduced bandwidth costs and increased processor capabilities in the end devices to carry metadata: standardized names and type information for the most common device information which can be used by applications for on-line verification of the integration and configuration of databases throughout the utility. Examples for measurement metadata are "unit", "offset", "scale", "dead band for report-ing", and description (see figure 2). This feature significantly reduces the cost of data integration, data management, and reduces down time due to configuration errors.

Figure 1: Modeling Example

The UCA object models are defined in terms of standardized types and services. These services (such as reporting by exception and select before operate controls) are defined in abstract terms, then mapped to messages in the underlying application layer protocol. UCA Version 2.0 application layer services for data acquisition and control functions in all of the profiles are provided by ISO/IEC 9506: Manufacturing Message Specification (MMS). The use of the standardized service definitions above MMS allow for 'future-proofing', in that new innovations in application layer protocols can be incorporated into future versions of UCA without disturbing the object model definitions.

Figure 2: Metadata Example

The MMS protocol, developed by the manufacturing community, supports real-time control and data acquisition. MMS defines a message structure supporting access to data, programs, journals, events, and other constructs common to real-time devices. These messages may be transported using many different underlying protocol stacks. The UCA makes use of a family of international protocols, organized according to the Open Systems Integration (OSI) reference model. The reference model allocates the communications functions to defined layers, then supports a variety of standards at each layer to allow for various price and performance options. Each industry sector then chooses from the options at each layer to define one or more profiles. The UCA in-cludes two primary 7 layer profiles, one using OSI standards and the other TCP/IP. The UCA also includes a 3 layer profile for use over serial links in low-cost devices.

Many parts of the UCA have been also progressed through the standards process as IEC international standards. The UCA approach to communication between control centers, power plants, and SCADA masters was developed as the Inter-Control Center Communications Protocol (ICCP). ICCP was later taken up by IEC TC57 working group 7 and standardized as IEC standards 60870-6-503 and 60870-6-802 (TASE.2). These standards define methods for using MMS to synchronize databases, as well as to perform scheduling, accounting, and other messaging.

The UCA Version 2.0 models, services, and protocols for substation devices are currently being used as the basis for IEC 61850. The initial committee drafts of IEC 61850 will be distributed to IEC member countries for balloting in mid 2000.

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"UCA" is a Trademark of EPRI, Palo Alto, CA, USA


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