Options and evaluation for the refurbishment of vibration damaged swer lines in Capricornia Electricity

Capricornia Electricity has an extensive Single Wire Earth Return (SWER) rural distribution network. As this SWER network ages, service problems resulting from excessive uncontrolled aeolian vibration are becoming apparent. In some SWER schemes the failure of hand ties and associated hardware is widespread. In the worst affected areas, there is evidence of damage to the aluminium wires in the ACSR conductor. As the current accepted practice is to reconductor these damaged lines, Capricornia Electricity is faced with major refurbishment costs. This thesis describes the investigative work undertaken to address the question of whether it is possible to reliably extend the service life of the vibration damaged lines without the need for reconductoring. In addition, the suitability of high tension line designs utilising small diameter conductors in terrain conducive to aeolian vibration is evaluated. While aeolian vibration is a well recognised and researched problem on transmission lines, relatively little work has been carried out on highly tensioned small diameter conductors in the range 5-lOmm. Furthermore, no specific work which addresses vibration problems in composite outer layer ACSR conductors could be located. In this research project, the current knowledge on conductor vibration and fatigue in transmission line conductors was reviewed, and the applicability of this knowledge to small diameter conductors was examined. It was established that field data on vibration modes and duration needed to be collected to allow for a satisfactory analysis of the vibration problem. Subsequent investigative work included the collection and analysis of a large volume of field data on the nature of the vibration problem, the establishment of the residual life of damaged conductors through laboratory testing, as well as experimental work to ascertain the effectiveness of various damping devices. Based on the available data, it was concluded that the application of appropriate damping systems would ensure the mechanical integrity of lines even where fatigue damage has occurred.