500 kV “Kartli-2” substation connects “Ksani-500” and “Zestafoni-500” substations. The length of the power transmission line is 164 km and includes 475 masts. The power transmission line was put into operation in 1968 and the АС400/51 cable is installed on it. The design load of the power plant is 900 MW.
A necessary condition for the sustainable operation of power transmission lines is the reliability of their insulation. As is known, according to the materials used as dielectrics, they are divided into porcelain, glass and polymer insulators. Of these, the most common are glass and porcelain insulators. Recently, due to the complexity of the manufacturing technology, high price and low reliability in operation, the production of porcelain insulators has decreased significantly and it has mainly been replaced by glass insulators. Using 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 transmission lines, it is not necessary to conduct periodic preventive tests of garlands, which is very time-consuming and practically impossible under the conditions of operation of operating power transmission lines. Damage to the glass insulators causes the plates to break, and during the technical inspection of the power lines, they can be detected even visually by any qualified personnel. In addition, there are often cases of vandalism on power lines.
It is worth noting that individual elements of power transmission lines have a certain working resource, after which the defects of the safe and promising porcelain insulators of EKG are visually difficult to notice, and their quantitative and qualitative assessment in Garlanda is impossible without putting them in the repair of power transmission lines and testing them.
Porcelain insulators can also be measured by their short circuit quantities. In conditions where there are currently no alternative lines of 500 kV power transmission lines, overlapping of insulators leads to emergency shutdown of the power transmission line. An emergency shutdown can lead to the shutdown of the country’s vital facilities and the largest part of the population. Accidents and large material losses that may occur to enterprises as a result of a sudden interruption of the technological cycle are not excluded. Porcelain insulators were installed on power transmission lines belonging to JSC “Sakrusenergo” at 500 kV EGK “Kartli-1”, “Kartli-2” and 330 kV EGK “Gardaban”. Their replacement on the so-called “Kartli-1” and “Kartli-2” began before the establishment of the company and until 2006 they were replaced on all intermediate masts and corner mast loops of these power transmission lines.
Porcelain insulators on 500 kV power stations “Kartli-1”, “Kartli-2” and 330 kV power stations “Gardaban” have been completely replaced, totaling up to 60 thousand pieces, including 40 on 500 kV power stations “Kartli-2” Up to a thousand porcelain insulators.
As for polymer insulators, we do not consider it appropriate to use them on company-owned power lines at this stage, because it is difficult to detect defects on them, and there is practically no experience of long-term operation of this type of insulators.
