On 27 July 2014, the conductor slipped out of a repair compression sleeve installed on one subconductor of Phase C in the No. 105–106 span of the 500 kV “Imereti” transmission line, resulting in an emergency outage of the line. A similar incident occurred on 5 June 2015, when the conductor slipped out of a repair compression sleeve installed on one subconductor of Phase B in the No. 334–335 span, again causing an emergency outage of the transmission line. In both cases, the conductor detached from repair compression sleeves that had previously been installed on damaged conductors in sections where intermediate transmission towers had collapsed.
Following the first incident, and in order to prevent similar failures, the damaged conductors in the No. 104–109 spans were replaced in 2014. Approximately 20 tones of conductor were used for these replacement works.
Similar conditions were identified on other sections of the 500 kV “Imereti” transmission line, namely in the No. 21–24, 45–48, 67–77, 173–174, 194–196, 323–328, 330–336, and 340–341 spans, where intermediate towers had collapsed during the period 1998–2006 and a large number of repair compression sleeves had subsequently been installed. To prevent the recurrence of such incidents, avoid major system disturbances, accidents, and significant material losses, and ensure the reliable and safe operation of the power system, 38,000 metres (approximately 56 tones) of AC 400/51 conductor, together with the associated line hardware, were replaced on the above-mentioned sections of the 500 kV “Imereti” transmission line in 2015.