What Is IEC 61850?

IEC 61850 is the international standard for communication networks and systems in power utility automation, written by IEC Technical Committee 57. It was first published in parts between 2003 and 2005 for substations and has since been extended to hydro plants, wind farms and distributed energy resources. Unlike older telecontrol protocols, it is a whole framework: a data model, a set of communication services, a configuration language and test rules.

The devices it connects are intelligent electronic devices (IEDs): protection relays, bay controllers, meters, merging devices and gateways. Before IEC 61850, a substation joined them with hundreds of hard-wired copper signals and a different vendor protocol at each level. IEC 61850 replaces much of that wiring with Ethernet, and replaces vendor point lists with names that describe what each value is.

Each IED is modelled as logical devices that contain logical nodes, standard functions with four-letter names. XCBR is a circuit breaker, MMXU a measurement, PTOC overcurrent protection and CSWI a switch controller. A value such as phase A voltage becomes a readable path like MMXU1.PhV.phsA, so a client from another vendor knows what it is reading without a register map.

The standard defines its services in the abstract, then maps them onto real protocols. Three mappings carry almost all substation traffic, and each has a different job and timing class.

MMS is the slower, routable client/server service a SCADA master or gateway uses to read values, receive reports and send controls. GOOSE and Sampled Values skip TCP/IP and run directly on Ethernet frames, usually in their own VLAN with IEEE 802.1Q priority tags, because a trip signal cannot wait behind file transfers. GOOSE repeats each message at short, then lengthening, intervals so a subscriber can detect a lost publisher.

IEC 61850 describes a substation in three levels: the station level with the SCADA and gateway, the bay level with protection and control IEDs, and the process level with the switchgear and instrument transformers.

The Substation Configuration Language (SCL), defined in IEC 61850-6, is an XML format that describes devices, their data models and the communication between them. Engineering tools from different vendors exchange the same files, which is what makes multi-vendor substations practical.

Substation networks sit close to high-voltage switchgear, so the equipment on them has its own environmental standard. IEC 61850-3 sets the general requirements for communication equipment in substations: electromagnetic immunity to switching surges and fast transients, insulation, wide temperature and power supply ranges. In North America IEEE 1613 covers similar ground.

Availability matters as much as speed. A spanning tree reconvergence is too slow for protection traffic, so process bus and critical station bus links often use PRP or HSR from IEC 62439-3, which send every frame over two paths for zero recovery time. Many station buses use a ring of managed industrial switches instead; several Antaira switches in our range list IEC 61850-3 Edition 2.0 for substations alongside ERPS ring recovery and VLANs. For station computers, a fanless rack mount server in our range lists IEC 61850-3 in its certifications.

Security is covered by IEC 62351, which adds TLS for MMS and message authentication for GOOSE and Sampled Values. The substation gateway is usually also where the network boundary to the wider SCADA system is enforced.

Transmission substations adopted IEC 61850 first, and many new high-voltage substations in the UK and Europe are now specified with it. Distribution networks are following as they automate, connecting reclosers, ring main switches and an RTU or gateway in secondary substations. Hydro plants use IEC 61850-7-410, solar, battery storage and other distributed energy resources use IEC 61850-7-420, and wind farms use the related IEC 61400-25 series. Our power and energy page covers the computers and networks we supply to these sites.

We supply the managed switches and industrial computers for substation and grid-edge projects with their network, operating system and protocol software configured as standard. Send us your bay count, redundancy scheme and environmental limits, and we will specify the hardware to match.