In modern power automation systems, IEC 61850 and IEC 60870-5-104 are two of the most widely used communication protocols. While IEC 61850 is often associated with digital substations and smart grids, IEC 104 remains a dominant protocol for telecontrol and dispatch communications.
Rather than competing technologies, these protocols serve different purposes and often work together in the same power network.
What Is IEC 61850?
IEC 61850 is an international standard developed for Substation Automation Systems (SAS). Unlike traditional protocols that only define communication methods, IEC 61850 provides a complete framework for data modeling, device interoperability, and engineering integration.
Some key characteristics include:
- Standardized logical node-based data models
- Self-describing devices
- High-speed communication services such as MMS, GOOSE, and Sampled Values
- Strong interoperability between devices from different vendors
Because of these capabilities, IEC 61850 is widely used inside modern substations where real-time communication and coordination between protection relays, IEDs, and control devices are critical.
What Is IEC 104?
IEC 60870-5-104, commonly known as IEC 104, is an Ethernet-based telecontrol protocol derived from IEC 101.
It was designed primarily for communication between substations and remote dispatch centers across wide-area networks.
Key features include:
- Master-slave communication architecture
- Support for spontaneous event reporting
- Lightweight protocol structure
- Reliable operation over long-distance networks
- Low hardware and bandwidth requirements
For decades, IEC 104 has proven itself as a dependable solution for SCADA and utility control systems.
IEC 61850 or IEC 104: Which One Is Better?
The answer depends entirely on the application.
If the goal is fast, intelligent communication between devices inside a modern digital substation, IEC 61850 is usually the preferred choice.
If the objective is reliable communication between substations and dispatch centers over long distances, IEC 104 remains one of the most practical and widely adopted solutions.
In reality, most utilities do not choose one over the other. Instead, they use IEC 61850 for internal substation automation and IEC 104 for external telecontrol communication, allowing each protocol to perform the role it was designed for.
Why Power Systems Often Use Both Protocols
Many utilities operate mixed environments where both protocols coexist.
Within a substation, IEC 61850 enables high-speed communication between protection and automation equipment. At the same time, IEC 104 is used to transmit operational data from the substation to SCADA systems and dispatch centers.
This approach allows utilities to benefit from modern substation automation while continuing to leverage existing telecontrol infrastructure.
The Challenge of Integration
Because IEC 61850 and IEC 104 use fundamentally different communication models, they cannot communicate directly.
IEC 61850 uses semantic data objects and logical nodes, while IEC 104 relies on predefined point addresses.
To bridge the gap, utilities typically deploy protocol conversion gateways that:
- Collect data from IEC 61850 devices
- Map information to IEC 104 point addresses
- Forward data to SCADA or dispatch systems
- Support bidirectional command transmission
This enables gradual modernization without requiring a complete replacement of existing systems.
Choosing the Right Migration Strategy
For most utilities and substation operators, the goal is not choosing between IEC 61850 and IEC 104. Instead, it is finding an effective way to integrate both technologies.
A growing number of industrial communication vendors now offer gateway solutions capable of translating between IEC 61850 and IEC 104, helping utilities modernize networks while preserving existing investments.
As digital substations continue to expand, hybrid architectures combining IEC 61850 and IEC 104 are likely to remain the most practical approach for many power automation projects.
Source: Adapted from COME-STAR Industrial Networking Technical Blog → https://www.come-star.com/blog/iec-61850-vs-iec-104-protocol-conversion-guide/
