The use of booster sheds to improve the performance of 800 kV multicone type insulators under heavy rain

Studies based on AC high voltage tests have been done at Cepel to investigate the performance of 800 kV busbar insulators under heavy wetting conditions. Insulators were tested as they are now used on site and also with different configurations of booster sheds. Images recorded by ultra-violet (UV) camera were used to help the investigations on the effectiveness of booster sheds. By comparing UV images of the insulator being stressed with high voltage under heavy rain with and without booster sheds, it was possible to observe how significant the reduction on the flashover formation process is when booster sheds are used. The effectiveness of booster sheds was also quantified by determining the disruptive discharge of the insulator with and without them. The results of these studies can also be considered as contribution to national and international standard technical committees to improving the standardized procedure for tests on ultra high voltage (UHV) insulators under heavy artificial rain. Subjects such as the clear definition of relevant UHV test procedure and test arrangements, including the use of UV camera, have to be taken into account.