A study on anti-contamination design of suspension insulators-a stress grading insulator

Insulator contamination is one of many serious problems for power systems. Outages due to insulator contamination flashover may affect a wide area and continue for a long time. Also, the corona noise causes radio and TV interference. Therefore, efforts have been made by many around the world to prevent such phenomena. Presently, fog type and semi-conducting glaze insulators have been developed, and successfully used. However, the former cannot suppress the corona and the latter has a subject to study from the viewpoint of thermal stability in heavy contamination conditions. A new concept insulator, with a stress graded zone on the bottom surface, has been studied. It has been determined that a dry band is not formed on this stress graded zone and a long dry band is formed at the first rib. This means the insulator has a high discharge starting voltage and high contamination withstand voltage.