The backbone of the electrical network, which provides transmission and distribution of electric energy is the electrical substation, consisting of switchgear, transformers and auxiliary equipment. In the distribution device (EDM) includes switchgear, control equipment and protection, ability to distribute electricity to individual consumers, providing them with reliable electricity supply, in both normal and emergency mode network. Switching equipment and devices of substations and distribution devices during their operation require constant attention from the electricians. To ensure a high level of technical state of equipment and technical operation of the Rules provides for a number of measures for its maintenance and repair. For continuous and trouble-free operation of substation equipment, switchgear and transmission lines with special schedules and plans are determined by the timing of their periodic examinations, preventive testing, as well as systematic prompt service. Preventive maintenance include maintenance of electrical equipment and technology indicators at the design level and calculated values (the replacement of individual parts and assemblies), which provides long-term, reliable and efficient operation of equipment..