In recent years, the Portuguese utility, EDP Distribuicão, has devoted much effort to a program aimed at analysing and improving the performance of its distribution network. As part of this process, a significant number of outages were discovered to be related either to environmental factors (e.g. lightning, pollution and birdlife).
Several background studies were made of overhead line performance from the perspectives of lightning, pollution and birdlife. Similarly, laboratory tests of insulators were carried out in order to evaluate the basic lightning insulation level to be used for equipment on the network.
This edited article, contributed by Antonio Oliveria Chaleira of EDP Distribuicão and Pedro Nunes of associated testing facility, Labelec, summarizes the findings of this evaluation. It also discusses individual case studies highlighting the improved insulation co-ordination methodology now being adopted by the utility.
