One of the most complex disciplines in electrical engineering is the protection of electrical systems, which not only requires a good understanding of the various components of the electrical system and their behaviors, but also good knowledge and analysis. abnormal circumstances and breakdowns that can occur in any element of the electrical system. Additionally, the rapid evolution and development of relay principles as well as their technologies are additional factors that require people working in this field to continually expand and update their knowledge. In this article, we have tried to highlight the evolution of protection relays from the appearance of electrical energy to the present day. We have also tried to predict future prospects and trends in this field.I. IntroductionThe protective relay is an integral part of any electrical power system. The fundamental goal of system protection is to quickly isolate a problem so that unaffected parts of a system can continue to operate. Protection relays are the decision-making device in the protection scheme [1]. These relays have experienced, over the course of more than a century, a significant evolution in their functionalities and technologies. Each change brings its chances and improvement both technically and financially. In this article, we have tried to shed light on the evolution of protective relays from the appearance of electrical energy to the present day. We have also tried to predict future prospects and trends in this field.II. Historical BackgroundSince the early days of the advent of electrical power, the need for devices to prevent undesirable events in the electrical system has been prescribed. The history of protective relays refers to more than...... middle of paper ... ...NG, vol. 60, no. 5, 2009.[21] Internet forum: “Suggestions from an experienced relay specialist”, http://rza.communityhost.ru/.[22] V. Gurevich, "PROBLEMS OF ASSESSING THE RELIABILITY OF RELAY PROTECTION", Электротехнические комплексы и системы управлен ия, no. 3, pages 56 to 59, 2010.[23] A. ABDELMOMENE and H. BENTARZI, "Reliability Enhancement of Power TransformerProtection System", Journal of Basic and AppliedScientific Research (J. Basic. Appl. Sci. Res.,2(10)10534-10539, 2012).[24] USNRC, “Development of Quantitative Software Reliability Models for Nuclear Power Plant Digital Protection Systems,” United States NuclearRegulatory Commission, Office of NuclearRegulatory Research, 2011.25] IAEA, “Modern Instrumentation and Control for Nuclear Power Plants: A Guide.” InternationalAtomic Energy Agency, Vienna, 1999.