DC vs. effects of thin film surface flashover

Modern energy systems are continually subject to failure from surface flashover of insulators. Little is known about AC and DC surface flashover in normal atmospheric pressures and temperatures. A greater general understanding of this phenomenon is needed to design modern energy systems with a higher tolerance for this failure process. Flashover in the past been has shown to occur primarily at a junction between the insulator, conducting medium and air which is known as the triple point. The focus of this initial study is on the adverse effects that AC and DC flashover have on conductive thin film geometry. The thin film is metallized polypropylene and is cut into strips measuring 12" X 3/4" to be representative of long path flashover in contaminated energy systems. Each strip of thin metallized film is then subjected to a voltage pulse of 2500 V/sub ac/dc/. Preliminary results have shown a significant difference of output energy from a pulsed AC to a pulsed DC configuration. The AC configuration yields more intense flashes of light as compared to the DC application. Upon further investigation, the conformity of the AC flashover remained consistent as voltage and film length were scaled down linearly in stages to 150 V/sub ac/ and 3/4" respectively. The DC configuration, when scaled down, did not experience any flashover at low voltages. These initial studies are to be extended in the future by developing a valid model to explain these significant phenomena.