1 Practical Applications of Ethernet in Substations and Industrial Facilities Craig Wester IEEE Member GE Digital Energy Multilin 20 Technology Pkwy, Suite 300 Norcross, GA 30092 USA Mark Adamiak IEEE Fellow GE Digital Energy Multilin 530 Swedesford Rd, 2 nd Floor Wayne, PA 19087 USA Abstract - This paper is a tutorial in Ethernet communications and architectures. The defacto LAN standard throughout the world is Ethernet and the worldwide investment into this technology dwarfs that of investment into any other LAN standard. Speed, fiber support, multiple services and protocol support, and the emergence and usage of the IEC61850 protocol have resulted in an increase in the installation of Ethernet within substations and industrial facilities. There are many practical aspects associated with the application of Ethernet within the substation and industrial facility. This paper will address Ethernet fundamentals and will attempt to cover the most common elements of an Ethernet architecture from media selection, requirements for protective relaying systems, managed Ethernet Switch functions and terminology relevant to the protection relay engineer (such as VLAN, RSTP and QoS), network topology (ring, star, mesh, redundancy) and high speed recovery of redundant ring networks. Architectures for different applications will be reviewed, such as SCADA and GOOSE messaging. The intent of this paper is to educate the non-IT person, such as the protective relay engineer, on Ethernet fundamentals that are important to protective relaying applications. I. INTRODUCTION Modern utility and industrial sites have evolved into complex operations that perform many functions and require a wide variety of Intelligent Electronic Devices (IEDs) and controls to work properly and safely. To automate these environments, these IEDs need to work in close concert. Today, organizations are moving from coordinating these IEDs using low-speed serial connections, to implementing high- performance networks built from Optical, Wireless, and Ethernet technologies. These modern networks enable quick, reliable communications that allow critical IEDs to be managed, analyzed, or controlled from a single or multiple locations. Taking the next step from automating a single site, organizations have begun to interconnect their various facilities to create larger, high-speed networks that allow control and monitoring from any location attached to the network. Many different technologies can be used to network together different sites. Over the past decade, Ethernet has become a popular networking technology because of its low cost, high bandwidth, and versatile support for multiple applications such as voice, video, and data. Additional benefits of networking IEDs include the ability to securely access the IEDs from anywhere within or outside the facility. Engineers and maintenance technicians can have remote access to IED settings, informative and historic data to assist in post fault diagnostics from the networked IEDs. Technological advancements in IED hardware design and the development of high-speed peer-to-peer communication protocols have resulted in a new generation of IEDs. These protective and control IEDs have the capability to accept multiple levels of current and voltage inputs and to analyze these values at significantly increased speeds. The main advantages of using these microprocessor-based IEDs are simplification of the device-to-device wiring, component cost reduction, increased system reliability and extensive data recording capabilities. An efficient way to apply these microprocessor-based IEDs and obtain a reduction in device-to-device wiring is to use high-speed peer-to-peer IEC61850 Generic Object Oriented Substation Event (GOOSE) messaging between the protective IEDs. GOOSE is a user-defined set of data that is “Published” on detection of a change in any of the contained data items. With binary values, change detect is a False-to- True or True-to-False transition. With analog measurements, IEC61850 defines a “deadband” whereby if the analog value changes greater than the deadband value, the GOOSE with the changed analog value is sent. IEC61850 uses an Ethernet connection as the physical medium of communication between the protective IEDs. Logical I/O via Ethernet communications is used in place of traditional hard wire to exchange the information between the protective IEDs. The information sent over the network might include connected device I/O, protective element statuses and programmable logic states. Modern IEC61850 implementations are able to send messages between protective relays at speeds of around 1 to 4 ms. Also, IEC61850 includes the capability of exchanging analog data between IEDs through IEC61850 GOOSE messaging, so actual values of currents and voltages are able to be sent over the high speed Ethernet network to other IEC61850 based IEDs. In addition, use of an Ethernet network allows simultaneous use of multiple protocols and services on the same hardware, such as Modbus, DNP (Distributed Network Protocol), IEC61850 and Phasor Measurement Units (PMU).