Effects of asymmetrical algal distribution on the AC flashover characteristics of bio-contaminated silicone rubber insulators

•Effects of asymmetrical distributed algae contaminates of flashover characteristics were evaluated quantitatively based on triangle plate model.•At continuous algae column condition, radial growth ratio of algae played an important role in the decreasing of flashover voltage, because insulator surface transferred into hydrophilic and insulation resistance of the specimens plummeted after algae colonization.•At intermittent algae column condition, axial growth width negatively affected the flashover voltage.