Simulation Of The Electric Field In The Condition Of Contamination And Local Defect Of 10kV Contact Box

With the rapid development of electric power system, the switch cabinet has been widely used in the electric power system characterized by its simple constitution, small maintenance, fitness for a frequent manipulation and etc. Insulation is one of the key factors of security and stable operation of power equipment. Switchgear as an important member of the power system, to study its insulation performance is essential, and contact box as an important switchgear insulator, it very important to study the factors may lead to damage of the contact box insulation performance.At present, the research of high voltage insulation damage at home and abroad mainly focuses on the high voltage insulator, and from multiple angles, the cause of the damage of the insulator is analyzed. But there is little research on the insulation damage of the contact box inside the switch cabinet. In this paper, a three-dimensional model of the switch cabinet bus bar is proposed. The influence of two cases analysis of the pollution and the bubble defect on the contact box is analyzed from the point of view of the electric field.Firstly, research status of contamination detection, flashover, bubble discharge were introduced, analyzed the theoretical basis of calculating the electric field. And then we simply introduced the simulation software ANSYS used in the research, and introduces the process of calculating the electric field of finite element method in detail at the same time.Secondly, with the help of finite element analysis software ANSYS, establishing switchgear bus room three dimensional model, the situation like contact box surface with dry contamination, wet contamination, dry belt, local filthy that may result in damage to the insulation of contact box are analyzed in detail. The simulation results show that:dry contamination has little influence on the electric field strength of the contact box, and has no influence on the performance of the contact box; the maximum electric field strength on the surface of the contact box during normal condition is 10 times of that of wet pollution, but the leakage current is 107 times of the normal condition; the electric field strength at the edge of the drying belt is 5 times of that of the normal condition.Thirdly, we analyzed the distribution of electric field when the contact box with different positions and different sizes bubble defects in detail. The results show that the closer the position of the switchgear cabinet, the electric field distortion more big in the bubble defects, it easier to cause the bubble gas discharge.Finally, the insulation performance of the contact box under standard lightning impulse withstand voltage is analyzed. Two representative cases are selected for analysis, single phase and three phase shocks were applied to them respectively. The results show that the lightning impulse increases the electric field intensity on the surface of the contact box, and the electric field intensity in the internal local area of contact box can reach the air breakdown field strength.