Breakdown Process Experiments of 110- to 500-kV Insulator Strings Under Short Tail Lightning Impulse

Lightning is always a major cause of outages in power systems during these years, the description of insulator string breakdown process is a key part in lightning back flashover analysis. This paper builds a model to accurately depict the insulator breakdown process, which is applied to typical porcelain insulator or typical composite insulator under positive or negative impulse. The breakdown experiments of insulators of different string lengths for 500-, 220-, and 110-kV transmission lines are carried out under short-tail impulse. For comparison, the insulator breakdown experiments under standard lightning impulse are done as well. Then, utilizing the records of voltage, current data, and photos taken by high-speed cameras, the leader progression model is developed. Finally, the models are validated by being embedded in PSCAD software.