Quantifying the Vulnerability of High Voltage Power Transmission Systems to Volcanic Ashfall Hazards

Abstract

Insulator flashover initiated by volcanic ashfall contamination compromises the reliability of high voltage transmission systems. Research at the University of Canterbury has identified the properties of volcanic ash most significant in causing the electrical breakdown of insulators due to ‘flashover’. This paper describes our current quantitative research programme. The research includes development of a new testing methodology to characterise the electrical resistance of volcanic ash samples of varying composition, grain size, soluble salt content, compaction and moisture content have been analysed to better understand the properties influencing 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 laboratory experimentation. Results to date indicate that the electrical reistance of volcanic ash decreases with increasing soluble salt content, water content, compaction and grain size. Early contamination testing has demonstrated the adverse affects of wet volcanic ash on energised insulator strings.