This book explores the physical principles governing the distribution of alternating currents exceeding 1000 A at frequencies ranging from 50 to 10,000 Hz in conductors used in industrial and energy installations. It provides a comprehensive overview of both theoretical and experimental studies on the skin effect and proximity effect in single-phase conductors, as well as the power transfer effect in three-phase conductors. The author offers recommendations for the optimal design of conductors, taking into account all three effects mentioned. The material presented in this book systematically organizes data published in technical literature, primarily from foreign sources, and includes some original research. This book is intended for electrical engineers involved in the design, installation, and operation of electrical systems with high-capacity alternating current conductors.