This book examines key issues in ensuring the operational reliability of energy facilities. In this regard, it analyzes mathematical models of diagnostic signals that arise during the operation of power equipment, reviews the main findings of research into their characteristics, presents diagnostics methods for selected types of electric power and heat engineering equipment, and covers a range of diagnostic and monitoring systems and devices for power equipment. Given its scope, the book offers a valuable resource for researchers, engineers and specialists, as well as instructors and graduate students at institutions of higher learning.