Power engineers of Samara Distribution Grids, a branch of IDGC of Volga, JSC (a member of Rosseti Group of Companies), proceeded to replacement of insulators at 0.4-110 kV power transmission lines. The operations are performed within the framework of the annual repair program. The insulators are designed to insulate wires from supporting structures of power transmission lines and its fasteners. As a result of long-term operation they lose their insulating properties which may lead to their failure and de-energizing of the power transmission line. Within the framework of the repair program, defective and worn-out insulators will be replaced with modern analogs which are more reliable and tolerant to environment conditions. All in all, within the framework of 2015 repair program, power engineers of Samara Distribution Grids will replace about 22,500 insulators at 0.4-110 kV power transmission lines. Completion is scheduled for this September. Large-scale replacement of insulators will make it possible to significantly improve reliability of power supply to consumers of the entire Samara region, and it will also contribute to smooth and continuous operation during 2015-2016 autumn-winter season.