RESEARCH ON ICING FLASHOVER CHARACTERISTIC OF DIFFERENT SHED TYPE COMPOSITE INSULATORS

With the global climate change, icing has become a common problem to China power system. Flashover problems caused by icing insulators have a serious threat to the safe operation of transmission and substations. It may result in tripping accidents, causing huge economic losses. In this paper, the artificial simulation icing flashover tests of ultra high voltage composite insulator with different shed structures (ordinary shed and anti-icing shed) have carried out in the environmental climate chamber of National Engineering Laboratory. A certain power frequency voltage applied on insulator string sample between the whole icing process, the environment temperature in the test chamber is -10 °C, the conductivity of water which used to icing is 100 μ S / cm, the temperature of water is 4 °C, the thickness of ice coating is about 13-15mm. The test result shows that the flashover voltage values are not same with different insulator shed. When equivalent salt deposit density p ESDD is 0.08mg/cm 2 , the flashover voltage gradient of composite insulator with ordinary shed is 54.4kV/m, but the flashover voltage gradient of anti-icing type insulator is 61.0-69.4kV/m, which increased about 12%-27% than the ordinary shed type, and the increasing amplitude of flashover voltage is proportional to the number of anti-icing shed. According to test phenomenon, we can find obviously that anti-icing shed of insulator is very useful to prevent ice bridged. Based on the analysis of the test results, this paper give the reasonable external configuration of ultra high voltage transmission lines to prevent icing flashover which is very important to improve the reliability of UHV transmission project in ice covered condition.