Computational analysis of the electrostatic environment and flashover performance of a suspension linkstick for live-line work on high voltage power lines

What are the root causes of recent live-line tool flashovers at electric field gradients of less than 100 kV/m when tools are supposed to withstand three times that stress? Computer simulations of electrical discharges from the head of the tool connected to the energized conductor suggest a role of highspeed surface partial discharges in initiating the flashover process.