Insulator flashover initiated by volcanic ashfall contamination compromises thereliability of high voltage transmission systems. Research at the University of Canterbury hasidentified the properties of volcanic ash most significant in causing the electrical breakdown ofinsulators due to ‘flashover’. This paper describes our current quantitative research programme.The research includes development of a new testing methodology to characterise the electricalresistance of volcanic ash samples of varying composition, grain size, soluble salt content,compaction and moisture content have been analysed to better understand the propertiesinfluencing the conductivity of volcanic ash. This has allowed the creation of a physically,chemically and electrically equivalent ash proxy to be used for current and future laboratoryexperimentation. Results to date indicate that the electrical reistance of volcanic ash decreaseswith increasing soluble salt content, water content, compaction and grain size. Earlycontamination testing has demonstrated the adverse affects of wet volcanic ash on energisedinsulator strings.
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