Conduction and breakdown processes in gases, vacuum, liquid dielectrics, and solid dielectrics are considered in this book, as well as overvoltage protection of high-voltage and medium-voltage transmission lines, substations, and electrical machines. Innovations in the field of overvoltage diagnostic methods are analyzed. The book is devised for students and specialists in the field of power and electrical engineering. It is written in Latvian language, contains preface, 5 chapters, 103 illustrations; total amount of this work is 199 pages. Bibliography includes 122 sources.