500kV ETL Khartli-1 connects substations Zestaponi 500 & Ksani 500, total length of the line is 91km and contains 249 power towers. The line was put in operation in 1968 and it’s designed load is 900MW. One of the essential conditions for the maintenance of power transmission lines, as well as the safety of personnel and the population living along the OHL and the observance of sanitary norms is the existence of a minimum allowable dimension between the OHL wires and the ground.
For a power line of the same voltage, the distance between the wires and the ground is one of the defining conditions for the electric field voltage, and it increases with decreasing dimensions.
Dimensions are usually restored by cutting the ground under the power line, or, if possible, by stretching the wires. Nevertheless, there are cases when such methods make it impossible to bring the size within the norm. For example: between 500 kV NT88-N209 towers in Mali, dimension to the dam separating the Aragvi River and the Saguramo-Natakhtari water pipeline, on which the road was arranged, was 5 meters instead of the standard 9 meters. The road to the dam was blocked and traffic was banned. A similar situation was on the Gombori section of the Tbilisi-Telavi highway. Where the N98-N99 Mali wires of the OHL “Kartli-1” intersect the road, the distance from the wires to the road surface was 7 meters, which is a gross violation of the design norm for crossing the roads. Presumably, during the rehabilitation of Gombori Road in this area, the road surface mark was raised compared to the previous one. In order to rectify the situation, the project was developed by the project organization “Energoxelproekt”, which envisaged the addition of one corner and one intermediate tower in the above-mentioned two malls, which was implemented in 2013, thus removing the existing problem.
In 2018, the damaged ASS0000 / 51 type cable with a length of up to 10 kilometers was replaced at the Kartli-1 HPP, on which repair clamps and bandages were installed for a long time. We considered the performance of this work as a priority, because from similar repair clamps in the summer of 2014 and 2015, during the summer of 700 kW on the 500 kV OHL Imereti, a wire was pulled out, which caused an emergency shutdown of the power line.
Porcelain insulators with glass insulators (up to 15 thousand pieces) have been completely replaced on 500 sq. M. “Kartli-1”. In addition to porcelain insulators have also been replaced by highly contaminated insulators, which in certain meteorological conditions cause a conductive and power line emergency shutdown. 500 kV OHL “Kartli-1” and 330 kV OHL “Gardabani” in the territories of Marneuli and Gardabani municipalities pass through the area of strong industrial and field dirt (thermal power plants, metallurgical plant, cement factories, agricultural lands, etc.). Removal can not be done by any chemical or mechanical means.