Among the options to resolve contamination problems on overhead lines is specifying greater creepage distance on insulators or using silicone rubber materials – or both. The latter solution can be achieved through a silicone housing, as in the case of a composite insulator, or by application of a silicone coating over a glass or porcelain insulator. In past decades, RTV silicone coatings have been used mainly at substations but this remedial measure is now being used by utilities on overhead line insulators as well. Here, application of the silicone coating can be performed directly on insulator strings on the line, on site but before being installed on towers or in the factory of the insulator supplier before delivery to site. Moreover, current trends demonstrate that silicone coated toughened glass insulators are now being selected from the design stage rather than only to resolve pollution problems. Indeed, this market is currently expanding, including for projects where polymeric insulators are no longer first choice.
Millions of silicone coated toughened glass insulators are now in use in countries across the globe. These have been systematically installed in harsh conditions where otherwise composite insulators would have been required. The main drivers for the decision by utilities to employ a coated insulator solution instead of composite insulators has been perceived long-term reliability, improved capability for live line work and relative ease of inspection. All these factors represent major benefits of glass insulators compared to other technologies.
Attend the 2017 INMR WORLD CONGRESS in Barcelona-Sitges from November 5 to 8 to hear a paper by Fabien Virlogeux of Sediver. He will outline some of the projects where silicone coated glass insulators have been used in a variety of service environments and explain the benefits of this technology through field experience and follow up analysis.