Electrical performance measurements of artificially and naturally aged polymeric insulators

Polymeric insulators are widely used in North America as replacements for ceramic insulators in power overhead line applications. Such insulators are subjected to a variety of environments some of which can cause degradation of performance. The Canadian Electrical Association therefore sponsored a project to develop a satisfactory method of assessing the level of performance to be expected from a polymeric insulator over its lifetime in service. This project included the development of three different artificial aging procedures, using a set of insulators from four manufacturers as test samples. Insulators of the same design were energised at three sites with quite different characteristics to give naturally aged and polluted test specimens for laboratory measurements. Various diagnostic tests were used to measure the performance of the naturally and artificially aged insulators, and the results of these tests are discussed by the authors.