Digital Protective Relay

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In electrical engineering of power systems, a digital protective relay uses a microcontroller with software-based protection algorithms for the detection of electrical faults. Such relays are also termed as microprocessor type protective relays. The digital protective relay, or numeric relay , is a protective relay that uses a microprocessor to analyze power system voltages and currents for the purpose of detection of faults in an electric power system. The relay applies A/D conversion processes to the incoming voltages and currents. The relay analyzes the A/D converter output to extract, as a minimum, magnitude of the incoming quantity, commonly using Fourier transform concepts. Further, the Fourier transform is commonly used to extract the signal's phase angle relative to some reference, except in the most basic applications.