IEC 61850 for Substation Automation: What EPC Contractors and Engineers Need to Specify

Modern substations increasingly depend on communication networks as much as conventional electrical wiring.

Protection relays, switchgear, bay controllers, meters, SCADA gateways and other intelligent electronic devices must exchange information rapidly and reliably. For utility, renewable energy, mining and industrial projects, this makes the communication architecture an important part of the overall electrical design.

IEC 61850 substation automation provides a standardised framework for communication between intelligent electronic devices used in power utility automation. The IEC 61850 series covers communication models, engineering methods and system requirements for interconnected devices. The IEC published an updated introduction and overview, IEC TR 61850-1-1:2026, in February 2026.

However, specifying simply that “the substation shall comply with IEC 61850” is not enough.

EPC contractors and engineers need to define protection functions, GOOSE messaging, network architecture, SCADA interfaces, time synchronisation, redundancy, testing responsibilities and interoperability requirements.

These decisions should be made during engineering rather than left entirely to the equipment supplier.

IEC 61850 Is More Than a Communication Protocol

IEC 61850 is sometimes treated as another alternative to protocols such as Modbus or DNP3.

In practice, its scope is broader.

It provides a standardised data model and engineering framework that allows intelligent electronic devices from different manufacturers to exchange information in a structured manner.

The objective is not simply to move data from one device to another. It is to create a common framework for protection, control, monitoring and automation functions across the substation.

A typical substation automation system may integrate:

• Protection relays

• Bay control units

• MV and HV switchgear

• Transformer monitoring devices

• Revenue and operational metering

• SCADA gateways

• Remote terminal functions

• Time synchronisation equipment

• Network switches

• Engineering workstations

This architecture can reduce dependence on large quantities of conventional point-to-point control wiring while improving access to operational and diagnostic information.

But the benefits depend heavily on how the system is engineered.

Start With the Protection and Control Philosophy

The first step in an IEC 61850 project should not be selecting Ethernet switches.

The project should begin with the electrical protection and control philosophy.

Engineers need to determine which protection functions are required and how signals will move between devices.

An IEC 61850 protection relay may provide functions such as overcurrent protection, earth fault, transformer differential, busbar protection, breaker failure, voltage protection and interlocking.

The specification should clearly identify which functions remain hardwired and which are permitted to use network-based communication.

This distinction is important for critical signals such as protection trips.

Define Signal Responsibilities Clearly

The project team should establish whether signals including breaker position, interlocks, blocking signals, transfer trips and breaker failure initiation will use conventional wiring, GOOSE messages or a combination of both.

The specification should also identify fallback requirements.

For example, does a protection trip require a hardwired backup?

Can an interlocking function depend entirely on network communication?

What happens if one network switch fails?

These decisions belong to the protection philosophy, not just the telecommunications specification.

GOOSE Messaging Must Be Engineered, Not Simply Enabled

GOOSE stands for Generic Object Oriented Substation Event.

It enables rapid peer-to-peer exchange of event information between intelligent electronic devices.

In practical substation applications, GOOSE messaging may be used for signals such as:

• Protection trips

• Interlocking

• Breaker failure initiation

• Blocking signals

• Transfer schemes

• Automatic transfer logic

• Busbar-related signals

IEC network-engineering guidance specifically addresses the transmission of protection-related information using GOOSE and the requirements surrounding topology, redundancy and time-critical communication.

Why GOOSE Can Simplify Substation Wiring

In a conventional design, one relay may require multiple physical wires to exchange binary signals with another relay or switchgear panel.

With GOOSE, the relevant information can be transmitted over the substation communication network.

This can reduce copper wiring and make more information available between devices.

However, replacing wires with Ethernet does not remove engineering responsibility.

The network becomes part of the protection system.

Bandwidth, redundancy, network configuration, message supervision and device behaviour during communication failures must all be considered.

Define GOOSE Signals Before FAT

A common mistake is leaving GOOSE mapping until equipment commissioning.

The project should instead define the required publisher and subscriber relationships during detailed engineering.

Documentation should identify which IED publishes each signal, which devices subscribe to it and what function depends on the message.

This information should be reflected in the system configuration and tested before delivery.

Communication Architecture Determines System Reliability

An IEC 61850 system requires an engineered communication network.

Network architecture should consider both normal communication requirements and credible equipment failures.

Typical elements may include managed Ethernet switches, fibre-optic communication, redundant network paths, gateways and time synchronisation systems.

IEC TR 61850-90-4 provides guidance on engineering local-area networks for IEC 61850-based substation automation, including topology, network redundancy and clock synchronisation.

Network Redundancy Should Match Substation Criticality

Not every project requires the same level of communication redundancy.

A small industrial substation may have different availability requirements from a major grid connection substation.

For critical applications, the design may need redundant communication paths so that a single network failure does not disable important protection or control functions.

The project specification should define the required redundancy philosophy rather than simply asking the vendor for a “redundant IEC 61850 network”.

Network switches, power supplies and fibre routes should all be considered.

Physical separation can also matter. Two communication paths installed through the same vulnerable cable route may not provide meaningful resilience against a common failure.

IEC 61850 Switchgear Requires More Than an Ethernet Port

Modern MV and HV switchgear can integrate intelligent protection, control and monitoring equipment.

But specifying IEC 61850 switchgear should involve more than requesting an Ethernet-capable protection relay.

The switchgear package may need to coordinate:

• Circuit breaker status

• Disconnector and earth switch position

• Protection trips

• Local and remote controls

• Interlocking

• Metering

• Alarm signals

• Trip circuit supervision

• Arc protection

• Equipment condition signals

Leistung Energie's existing MV switchgear specification guidance recommends defining communication protocols, SCADA interfaces, time synchronisation, remote control, alarm signals and protection requirements as part of the overall switchgear package rather than leaving relay selection undefined.

SCADA Integration Should Be Designed Early

The station SCADA system needs access to operational data from multiple devices.

Typical information may include breaker status, alarms, currents, voltages, power, protection events and equipment condition.

IEC 61850 can provide a structured method for exposing this information, but the project still needs a defined SCADA philosophy.

Engineers should identify:

• Required measurements

• Alarm priorities

• Remote commands

• Control authority

• Event recording

• Time stamps

• Sequence-of-events requirements

• Gateway requirements

• Control-centre interfaces

Where legacy equipment or other communication protocols are present, gateways may be required.

The IEC published IEC TR 61850-80-5:2026 to provide a mapping framework for systems using IEC 61850 together with Modbus-based devices through gateways, highlighting the continuing importance of integrating IEC 61850 systems with existing communication environments.

Interoperability Does Not Mean “Plug and Play”

One of the major reasons for using IEC 61850 is interoperability between devices from different suppliers.

However, interoperability should not be interpreted as meaning that every compliant device can automatically be connected without engineering.

Devices may support different functions, logical nodes, optional features, firmware versions or engineering tools.

IEC guidance on Basic Application Profiles specifically addresses methods for defining common functional behaviour and improving interoperable interaction between power utility automation functions.

Specify Device and Engineering Deliverables

For multi-vendor projects, tender documents should request clear information regarding:

• Supported IEC 61850 edition

• IED capability files

• Configuration files

• Data models

• GOOSE capabilities

• Time synchronisation

• Engineering software

• Firmware versions

• Cybersecurity requirements

• Configuration backups

The EPC contractor should also determine who owns the final system configuration files and whether they will be supplied in editable form.

Without these deliverables, future maintenance or relay replacement can become unnecessarily difficult.

FAT Must Test the System, Not Just Individual Relays

A relay can pass its individual factory test while the complete automation system still contains configuration errors.

For IEC 61850 projects, FAT should therefore verify system-level interactions.

IEC TR 61850-10-3 provides guidance for functional testing of IEC 61850 systems and specifically addresses verification of applications using communication interfaces such as GOOSE rather than conventional hardwiring.

Do Not Forget Site Acceptance Testing

Factory testing cannot fully reproduce the final installed network.

After equipment installation, Site Acceptance Testing should confirm that fibre links, network switches, relays, switchgear, SCADA and control-centre interfaces operate correctly together.

Changes made after FAT must also be controlled carefully.

A small relay configuration modification can affect GOOSE relationships or SCADA mapping elsewhere in the system.

Configuration management is therefore essential for a digital substation.

The final documentation should represent the system that is actually commissioned, not simply the design that originally left the factory.

What EPC Contractors Should Include in the Specification

A practical IEC 61850 specification should define more than one line stating compliance with the standard.

Specification Area	What to Define
IEC 61850 requirements	Applicable edition and project requirements
Protection relays	Required functions and approved interfaces
GOOSE	Signals, publishers, subscribers and criticality
Communication network	Topology, fibre, switches and redundancy
Switchgear	Controls, status, interlocks and relay integration
SCADA	Measurements, alarms, commands and gateway interfaces
Time synchronisation	Required method and accuracy
Interoperability	Multi-vendor requirements and file formats
Engineering files	Required configuration and backup files
FAT	Functional and integrated system testing
SAT	Final installed-system verification
Responsibility	Vendor, EPC and system-integrator boundaries
Documentation	Network drawings, signal lists and configurations

This information allows equipment suppliers to quote against a defined architecture and helps reduce technical assumptions during tendering.

Conclusion

IEC 61850 substation automation can provide a powerful foundation for modern protection, control, monitoring and SCADA systems.

But successful implementation depends on engineering detail.

Protection functions, GOOSE messaging, network redundancy, switchgear integration, interoperability, SCADA interfaces and testing responsibilities all need to be defined before procurement.

For EPC contractors, the most important principle is simple: do not treat IEC 61850 as a checkbox in the switchgear specification.

Treat the communication network and system configuration as part of the protection and control system itself.

A clearly engineered specification helps suppliers offer comparable solutions, reduces integration problems during FAT and commissioning, and provides a stronger foundation for the long-term operation of the substation.

Planning an IEC 61850-Based Substation?

Leistung Energie supplies medium-voltage and high-voltage electrical equipment for utility, renewable energy, mining, industrial and infrastructure projects.

If your project requires medium voltage switchgear, protection relay integration, SCADA interfaces or IEC 61850 communication requirements, these interfaces should be defined early during equipment specification.

Contact Leistung Energie Australia to discuss your switchgear, protection, communication and substation automation requirements for your upcoming project.