Intelligent electronic devices today are able to carry out an astonishing array of powerful functions. Through rapid evolution, intelligent modules are consistently added and these advances are game changing in utilities development. Intelligent protection relays can protect, monitor, control and measure grid conditions in real time all the way through the grid to distribution substations. Through device writing functions and relay system settings, values can be changed and separately stored.


An intelligent protection relay is first and foremost an intelligent electronic device that uses a microprocessor. Performing around 5-12 protection functions, these microprocessors detect faults and performs protective tasks like over-current release and reclosing using the relay inputs of current and voltage signals received via transformers. Extensive protection of three-phase lines is possible. Data is permanently stored, even if power is lost.


Today’s intelligent protection relays perform the accurate measurement of a number of factors related to current and voltage. Measuring current, voltage, apparent power, active power, reactive power, power factor and frequency, and even phasors, these digital relays are able to measure and respond protectively according to presets programmed in when the relay is first connected. Accurate readings and set responses enable the grid to perform in more predictable ways.

Monitoring and Control

Advanced monitoring and diagnostics are possible using intelligent protection relays. This level of effective monitoring and control has effects throughout the network. Radical changes in security, reliability and grid efficiency is possible through these highly automated processes that can be verified remotely in real time. Using these relays, outages can be reduced and fault areas limited and rapidly cleared from the grid.

Interlock Logic

Interlock schemes are usually hardwired with interlock status contacts to prevent unsafe switching when the intelligent protection relays operate in manual modes. These interlock schemes are state stable, failsafe and robust. Logic-based interlocking operations are performed via computer using buttons, switches or toggles on a video or panel interface.

Self Diagnosis

Intelligent protection relays can self diagnose. For events to be recorded and quick responses to faults made possible, the relays are fitted with a self diagnostic function. This allows the permanent monitoring of operation states and standard follow up activity once any problem sensed by the intelligent protection relay system. Messages will be displayed on an LED screen or panel, enabling response by dedicated personnel or in some instances, automated self healing.


The communications capability of intelligent protection relays allow for high communication speeds. The current measured values can be easily identified through each phase. Operation states, event data, fault data and self diagnosis information can be accessed in real time. Interoperability between intelligent electronic devices is possible using USB ports. Energy efficiencies and reduced manpower contribute to the grid becoming less of a burden on resources.

Keywords: protection relay system, Intelligent protection relays

By: Rosario Berry

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Article ID 1020581 (Views 723)

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