In many respects, this statement made nearly five years ago by internationally-known researcher Claude de Tourreil, is still true today. Although a set of initial guidelines for inspecting non-ceramic insulators have been recently issued by de Tourreil’s CIGRE Working Group, there is still widespread concern among
utilities about how to accurately assess the in-service condition of these insulators. For example, José Maria Muñoz of the Maintenance Department at Spain’s RED Electrica remarks, “non-ceramic
insulators present a material with which we are not yet very familiar and naturally we are anxious to avoid any problems. In order to know these insulators better, we feel we have to carry out evaluations to follow their history from when they are new to how they are ageing in service.”
In-service identification of defects which may ultimately lead to failure of non-ceramic insulators is obviously an area of special interest. This is because the alternate approach of taking down sample insulators to be sent for laboratory investigation is costly and may also involve a lengthy time delay before results are available. It was with this basic goal that the Swedish Transmission Research Institute (STRI) recently launched a major Project in this area.
According to Research Project Manager Igor Gutman, the overall aim of the two-phase project was to identify and elaborate upon the most effective in-service diagnostic techniques to detect specific internal defects which are likely to signal impending failure of a non-ceramic insulator. Within this overall framework, STRI researchers were also looking to determine any technique limitations and to establish what type of climatic conditions are optimal for in-service inspections.
