Which device is considered an Intelligent Electronic Device (IED) in an IEC 61850 system?

In an IEC 61850 system, a Protective Relay is considered an Intelligent Electronic Device (IED). IEDs are essential components in modern power systems that provide advanced functionalities such as protection, control, monitoring, and communication capabilities. Protective relays specifically offer protection by detecting faults in the electrical system and facilitating the necessary actions, such as tripping a circuit breaker to isolate the fault.

The importance of Protective Relays within the context of IEC 61850 lies in their ability to communicate and interact with other devices and systems through standard protocols, thereby enabling a more integrated and responsive power system. Their intelligence comes from their ability to process data, make decisions based on programmed logic, and communicate over the network, which aligns perfectly with the goals of IEC 61850 to promote interoperability and efficient data exchange among devices.

Other choices such as a Motor Starter, Substation Communication Bus, and Logical Node do play roles within the broader system but do not possess the full range of functionalities and smart capabilities that define an IED. Motor starters primarily serve to start or stop motors but do not inherently have the protective and communicative capabilities of a relay. The substation communication bus refers to the data transmission medium rather than an intelligent device. Logical nodes represent data models within