Life time of overhead transmission line supports
The article discusses issues related to the influence of climate impacts on the reliability of overhead transmission line supports. Natural phenomena that exert breaking forces on supports are wind loads and glaze deposits. The article provides an analysis of the life of supports that are vulnerable compared with other types of supports. This analysis was made based on the experience of operation of 220 kV and higher power grids owned by the Kazakh Company 1999-2013. Statistical data on support failures that happened in the period of 1966-1989 is also provided. The main support failures occurred during their operation are described. The support failure flow parameters are defined for the northern, western and southern regions of Kazakhstan. Probabilistic support failure models for the next six years are shown for these regions. To sum up, the results of the research, conclusions about the change in the number of failures as well as comparative figures of the flow parameters of overhead transmission line failures for the northern, western and southern regions of Kazakhstan are presented. The results showed that the support failure flow parameters in the northern region are higher than in other regions of Kazakhstan due to the effects of the severe climate. The probability of not exceeding climatic loads accepted as normative values in the Rules for Electrical Installations (7th edition) complies with the period of repeatability of standard climatic loads 1 time in 25 years.