The brochure describes the principle of operation, design, installation and operation of valve arresters, which are the main means of protecting the electrical equipment of power plants and substations from overvoltages. The brochure is a continuation of issue 118 (Electrician Library 1964) "Overvoltages and electrical strength of high-voltage insulation." This issue is supposed to publish the following brochure, which will describe tubular arresters, protective gaps, capacitors and lightning rods, which also serve to protect electrical installations from lightning overvoltages. The brochure is designed for electricians who maintain and install electrical networks and substations