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 addresses. 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 addresses. Protective Relays - Technical Seminar Nov 2016 - Copyright: IEEE 2 Abstract: Protective relays and devices have been developed over 100 years ago to provide “lastline”of defense for the electrical systems. They are intended to quickly identify a fault and isolate it so the balance of the system. The protection system must not react to faults in neighboring zones or high load currents. For electromagnetic relays, this was a main design characteristic. : 4 The first protective relays were electromagnetic. What is a relay; more specifically, what is a protective relay? The Institute of Electrical and Electronic Engineers (IEEE) defines a relay as “an electric device that is designed to respond to input conditions in a prescribed manner and, after specified conditions are met, to cause contact. The article provides an overview of protective relaying principles and their applications for high-voltage power system components. It covers the protection methods for generators, transformers, buses, and transmission lines using various relay types to detect and isolate faults efficiently.