Intelligent electronic device

[1] IEDs receive data from sensors and power equipment and can issue control commands, such as tripping circuit breakers if they sense voltage, current, or frequency anomalies, or raise/lower tap positions in order to maintain the desired voltage level.

The testing of setting files is typically one of the most time-consuming roles of a protection tester.

[citation needed] Some recent IEDs are designed to support the IEC61850 standard for substation automation, which provides interoperability and advanced communications capabilities.

IEDs are used as a more modern alternative to, or a complement of, setup with traditional remote terminal units (RTUs).

Alternatively, they can be connected to a substation RTU that acts as a gateway towards the SCADA server.