500 kV ETL “Kartli-2” connects the substations “Ksani-500” and “Gardabani-500”. The length of the power line is 164 km and includes 475 towers. The transmission line was put into operation in 1968 and has an AC400 / 51 wire installed on it. The design load of the ETL is 900 MW. A necessary condition for the sustainable operation of power lines is the reliability of their insulation. According to the materials used as dielectrics, they are divided into insulators of porcelain, glass and polymer type. The most common of these are glass and porcelain insulators. Recently, due to the complexity of manufacturing technology, high price and low reliability in operation, the production of porcelain insulators has been significantly reduced and it has been largely replaced by glass insulators. The use of glass insulators on power lines has a number of advantages. Compared to porcelain insulators, glass insulators are easier to detect defects. When using glass insulators on power lines, it is not necessary to conduct periodic prophylactic examinations of garlands, which is time consuming and practically impossible in the conditions of operation of the current power lines. Damage to glass insulators causes plates to break and can be detected visually by any qualified personnel, even visually, during a technical inspection of power lines. In addition, vandalism often occurs on power lines. It should be noted that individual elements of power lines have a certain work resource, after which the defects of safe and reliable porcelain insulators of the ETL are visually difficult to detect and their quantitative and qualitative assessment in Garland is impossible without repairing and testing power lines. Defective porcelain insulators are also possible with their short circuit quantities. In conditions where there are currently no alternative lines of 500 kV power lines, overlapping insulators will result in emergency power line failure.
A breakdown can cause the country’s vital facilities and a large part of the population to be cut off. Accidents and large material losses that may occur to enterprises as a result of abrupt termination of the technological cycle are not excluded. Porcelain insulators were installed on the transmission lines owned by JSC “Sakrusenergo” 500 kV ETL “Kartli-1”, “Kartli-2” and 330 kV ETL “Gardabani”. They were replaced by EGH “Kartli-1” and “Kartli-2” before the establishment of the company and until 2006 were replaced on all intermediate masts of these power lines and in the corners of the corner masts. 500 kV ETL on “Kartli-1”, “Kartli-2” and 330 kV ETL “Gardabani” Porcelain insulators have been completely replaced, up to 60 thousand pieces, including 500 kV ETL “Kartli-2” – 40 Up to a thousand pieces of porcelain insulator.
As for polymer insulators, their use on the power lines owned by the company at this stage is not advisable, as they are difficult to detect defects and there is virtually no experience of long-term operation of these types of insulators.