A Study on the Influence of Pollution Level and Humidity on Creepage Discharge Characteristics over Solid Dielectric/Air Interface

Summary

Manufacturers of medium voltage switchgear panel have been using solid materials such as SMC, in order to improve the dielectric strength of their products. They have also been carrying out researches on the influence of the insulation material properties on the creepage discharge characteristics over solid dielectric / air interfaces. Experimental investigation on the influence of pollution and humidity on the surface of solid material, however, is needed in designing an insulation structure of the medium voltage switchgear panels in the polluted areas such as industrial complex and inshore regions. Because, it has been reported that creepage breakdown could take place due to the presence of moisture, contaminants on the dielectrics surface and short creepage distance. In this paper, to secure the insulation safety for the various operating environments of switchgear panels, an experimental investigation on the creepage discharge characteristics over solid dielectric / air interfaces as a function of pollution level and humidity has been performed by using the disk type specimens made of SMC under AC voltage source. The creepage distance of disk specimens is simulated by choosing different disk diameters such as 100 mm, 200 mm and 400 mm. The pollution process of specimens was conducted in accordance with IEC 60507 and IEC 60815 - 1. All the results are compared with those of the virgin specimen without pollution as the reference. In conclusion, the creepage discharge voltage of specimens were decreased inversely proportional to the pollution level under high humidity condition, whereas the influence of the pollution level was investigated to be reduced under low humidity condition. Furthermore, there was difference at the creepage distance dependence according to pollution and humidity conditions. These experimental results could be used to improve the dielectric creepage strength of switchgear panel using solid materials such as SMC.

Additional informations

Authors

Kühnel Stefan, Bärsch Roland, Lambrecht Jens, Grunwald Martin, Geissler Daniel, Leibfried Thomas