Development of new methodology for insulators inspections on aerial distribution lines based on partial discharge detection tools

The necessity of improving the reliability of aerial distribution systems in Brazil has led to development and application of new techniques and tools aiming at prediction of problems related to transformers, insulators, cables and other major components of the network. In the case of insulators the traditional inspections consist of visual scans, however, have poor precision once they depend greatly on the ability and experience of the linemen workers. This paper discusses the partial results of the application of new tools to 15 kV class porcelain pin insulators in the ENERGISA distribution lines. These tools are based on the emission of infrared, ultraviolet, radio frequency and ultrasound by damaged insulators. Using these experimental tools a great amount of insulators were scanned and the suspicious units were removed from the structures. These insulators were submitted to visual inspection and evaluation through withstand and disruptive-discharge voltage tests. The results from these tests are compared with the results from the tools applied to the inspections in order to find out what are the more adequate tools for 15 kV porcelain pin insulator inspection. Additionally, the leakage current was analyzed in laboratory, having the RMS value and the waveform registered for further possible association with the insulators conditions.