Studying AC Flashover Performance of Suspension Insulators Under Natural Cold Fog and Wet Deposition Conditions

The electrical performance of insulators under comprehensive conditions including low air pressure, pollution and icing, is an important basis for the selection of external insulation. However, the problem of cold wet deposition has not attracted extensive and considerable interest in research. Based on flashover tests of suspension insulators in field test station, the AC flashover performance of insulators was studied. The results show that the duration of existence of the arc throughout the composite insulator surface in case of condensation was significantly lower than that in case of freezing fog flashover because of a change of the sheds surface roughness, which leads the arc melt the frozen fog droplets on the sheds surface and extends its flashover time. Compared with the flashover characteristics of the hydrophilic insulators in frost fog, the composite insulators exhibited clear arc extinguishing and arc starting phenomena. Moreover, the wind velocity has affected the flashover performance of suspension insulators in cold fog. Studying flashover characteristics of suspension insulators can contribute to the design of the external insulation of transmission lines and substations under natural cold fog and wet deposition regions.