What are IEDs (Intelligent Electronic Devices)?
An IED (Intelligent Electronic Device) is a microprocessor-based electronic device used in the energy and industrial sectors to collect data, analyse it and take decisions about controlling electrical systems — often without human intervention.
IEDs are essential in substation automation and are used for protection, measurement, monitoring and control of power networks.
🧠 What does an IED do?
An IED can perform one or more of the following functions:
- Measuring voltage, current, power, frequency
- Detecting faults such as short circuits or overload
- Automatically tripping electrical circuits (protection)
- Communicating with SCADA or DMS systems (via IEC 61850, DNP3, Modbus)
- Analysing data and executing logic (e.g. logic control units)
🔧 Examples of IED applications
| Application | Description |
|---|---|
| Protection relay | Automatically trips power on faults in the network |
| Meters & power quality analysers | Real-time Monitoring of energy consumption and power quality |
| Breaker control units | Operating circuit breakers |
| Remote terminal interface | Local interface to SCADA or DMS via various protocols |
📦 Typical characteristics of an IED
- Integrated logic: built-in PLC functionality or control unit
- Time stamping and synchronisation: critical for fault analysis
- Robust and real-time: designed for 24/7 operation under harsh conditions
- Communication protocols: support for IEC 61850, DNP3, Modbus, etc.
- Self-diagnostics: monitors its own health and status
🏭 Examples of IEDs in practice
- In substations of electricity companies (for Monitoring and protection)
- In smart grids for load balancing and fault isolation
- In industrial installations such as data centres, refineries or wind farms
🔄 IED vs. RTU
| Feature | IED | RTU |
|---|---|---|
| Intelligence | Takes decisions autonomously | Executes commands from SCADA |
| Typical use | Protection and control in power grids | Collecting data remotely |
| Protocols | IEC 61850, GOOSE, DNP3, Modbus | DNP3, Modbus, IEC 60870 |
| Location | In substation, directly at the equipment | At a remote location, as a collection point |
📌 In summary
IEDs are intelligent electronic devices that perform critical tasks in electrical systems, such as measuring, protecting and automatic switching — often without human intervention.