Lessons from 20 Years’ Experience with Composite Insulators on Transmission Lines by Glenn Stapleton
Powerlink is a government-owned network service provider that builds, owns and operates the extensive transmission network in Queensland, Australia, where some 30,000 non-ceramic insulators (NCIs) are in service and operate at 110, 132, 275 and 330 kV. This experience began about 20 years ago, when prevailing thinking and drivers were to install NCIs in large quantities on transmission lines. Back then, their service life was estimated to be 25 years in relatively clean environments, although insulators on certain lines were damaged shortly after installation due to bird pecking and chewing. Over the years, field inspection and laboratory testing were performed on NCIs removed from service to monitor for possible degradation over time. This testing was intended to estimate end-of-life so that replacements could be prioritized, scheduled and resourced for replacement before failure. An important consideration in this process was retaining the option to safely undertake replacement using live working methods. Over time, technical drivers and management strategy changed such that asset managers are now considering replacement strategies for whole NCI populations as well as managing them using fleet management approaches. This presentation discusses Powerlink’s experience across the whole life cycle of 3rd generation NCIs that are approaching projected end of life. Desktop models, with calibration using field inspection and laboratory investigation, are also presented as is a case study using three sub-populations of NCIs on transmission lines.