Flashover mechanism of non-ceramic insulators

George G. Karady

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


The contamination performance of non-ceramic (NC) insulators is better than porcelain insulators. The paper describes the pollution collection mechanism and concludes that silicone rubber insulators coiled more pollution than porcelain insulators. Long term exposure of silicone rubber insulators produces a thin layer of pollution, which is a mixture of dust, salt and silicone oil. Fog or morning dew produces droplets on the flat surfaces and forms conductive regions. Spot discharge starts between the regions, which reduces hydrophobicity. Simultaneously, dry-band arcing starts on the shank of the insulator. The two arcs join together, which leads to flashover. The flashover voltage of polluted NC insulators is significantly higher than porcelain ones. Insulator performance is measured with laboratory tests. However, salt-fog and clean-fog tests can give different flashover values.

Original languageEnglish (US)
Pages (from-to)718-723
Number of pages6
JournalIEEE Transactions on Dielectrics and Electrical Insulation
Issue number5
StatePublished - Dec 1 1999

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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