Study On DC Arc Characteristics And Its Influence Factors On Silicone Rubber Surface

Composite insulator pollution flashover always happens accidently and suddenly and composite insulators itself have hydrophobic recovery ability, therefore there is no agreement reached for composite insulator flashover characteristics and mechanism. In order to study the arc characteristics on the silicone rubber surface under DC high voltage, the dynamic behavior of the droplets on the silicone rubber surface, starting and development process of partial arc and volt-ampere characteristics are researched. The main research results are as follows:Water droplets on silicone rubber surface in the direct current field will produce deformation, stretch and vibration phenomenon. Dynamic model of water movement is established and force analysis is carried out in the process of water droplets deformation. The results show that the deformation of water droplets is influenced by the direct current field intensity, water droplet size, water conductivity and surface tension. On different hydrophobic levels of silicone rubber surface steady state of water is different, the higher the degree of hydrophobic, the smaller the droplet deformation degree.Arc discharge process on silicone rubber surface with discrete water droplets is divided into three stages: water droplets stretch, production of partial arc and the formation of flashover. Electric field simulation results on silicone rubber surface with discrete water droplets show that the reason why partial arc is starting is that the existence of the separation of water droplets led to the electric field distortion. Condition of partial arc starting is the field strength is greater than the critical value and the electric field distortion coefficient is greater than the critical value. The mechanism of the arc development is the electric breakdown rather than thermal breakdown. Research of on the influence of hydrophobic level, pressure and water conductivity to arc characteristic is studied. In the process of arc development under low air pressure, there will be floating phenomenon of arc, the lower the air pressure is, the more serious of floating phenomenon of arc. The starting and development of arc is influenced by various factors and conditions. Starting position of arc is always the position where the field strength is the biggest and it will always develop along the path where the hydrophobic is weakest.The DC arc E-I characteristics including the constants A and n on composite insulation material surfaces were determined in this paper. Moreover, intervening factors such as arc polarity, hydrophobicity levels of samples and atmospheric pressure were studied using a triangular composite silicone rubber sample. It was found that current and voltage values of partial arc don’t culminate at the same time on composite silicone rubber. The arc constants A and n, which were obtained by the way of nonlinear curve fitting, are obviously influenced with the polarity of arc, hydrophobicity levels and air pressure.