This presentation reviews the established principles and the advanced aspects of the selection and application of protective relays in the overall protection system, multifunctional numerical devices application for power distribution and industrial systems, and. This presentation reviews the established principles and the advanced aspects of the selection and application of protective relays in the overall protection system, multifunctional numerical devices application for power distribution and industrial systems, and. systems driven by Digital Intelligence (DI) to enhance the modernization and practicality of the course. By analyzing the application of DI technologies, such as big data, artificial intelligence, and the Internet of Things, in power systems, he study examines their impact on relay protection. Protective relays and devices have been developed over 100 years ago to provide “last line” of defense for the electrical systems. They are intended to quickly identify a fault and isolate it so the balance of the system continue to run under normal conditions. The selection and applications of. able sources such as wind and solar. Sequence Components and Fault Analysis: sequence impedance, fault calculations, Single line to ground fault, Line to ground fault with Zf, Faults in Power syst ional relays, Distance relays, Differential relays. Feeder Prot ction: Over current.