The textbook is intended for students of technical and professional educational institutions. The first chapter of the tutorial contains theoretical materials, which gives general concepts about relay protection, alarm, emergency protection and blocking. The second chapter describes the types of relays and their features. This chapter describes the connections and the advantages and disadvantages of the main types of relay protection devices. The third chapter describes the basic methods for checking and configuring relay protection. Also, the description of checks of relay equipment elements is given.