An Intelligent Electronic Device (IED) is a term used in the electric power industry to describe microprocessor-based controllers of power system equipment. It is used by the Energy sector to monitor and control electrical power devices such as circuit breakers, capacitors, and transformers. IED receive data from field sensors (I/O) and power equipment and can issue control commands. These commands include simple things such as tripping circuit breakers if they sense anomalies in voltage or current. They can also instruct system output to raise or lower voltage levels in order to maintain the desired level. Common types of IED include protective relaying devices, load tap changer controllers, circuit breaker controllers, capacitor bank switches, re-closer controllers, and voltage regulators.
Many owners/operators leave their IED with their “fresh out of the box” configurations. These default configurations, unfortunately, make it easier for those with ill intent to make changes to the operational parameters of the device. Furthermore, some owners opt to keep the extra communication programming ports active so they can view or make online changes from the shop or control room. Considering that modern IED are fully network aware, and in some cases, may have embedded services that facilitate remote administration, there is a valid concern for the cybersecurity of these devices.
The utilities which operated the power transmission stations were some of the first to use IED. This early use was not to comply with regulatory requirements, but to save money. The use of IED in this instance meant a highly paid technician would not have to drive to a potentially remote transmission station to retrieve data.