Research On Long Gap Discharge And Discharge Channel Under Low Pressure

Long air gap discharge is one of the basic research in the filed of high voltage.In recent years,China's energy development in the central and western regions has gradually increased.UHV AC and DC power transmission project has become the main way of power transmission,many transmission projects are applied at an elevation of approximately 4000 meters.As this altitude increases,the decrease of air density will result in the decrease of the insulation strength of air gap.According to the accual operation experience of power grid,the insulation characteristics of electrical equipment in low pressure are affected significantly,improper design will lead to an accident.Therefore,it is necessary to study air gap discharge in low pressure condition.To research the discharge characteristics of long air gaps under low pressure and breakthrough the limitation of chamber size to discharge length,a test chamber with polypropylene material as its main body was made in this paper,and a long gap discharge platform under low pressure was built,pressure and gap length are adjustable within 23Pa?100kPa and 600mm respectively.This paper carried out laboratory investigations of AC and DC discharges by vacuum test platform for 200?600mm rod-plane gaps within 2?60kPa.The relationship between discharge voltage U and pressure P of different gap length and voltage modes are obtained,the characteristics and the reasons of the curve are analyzed.At present,researchers at home and abroad have obtained the external characteristics of air gap discharge at high altitude,however,the study on the external characteristics and breakdown mechanism of air gap discharge channels in low pressure is not deep enough.Therefore,it is of great significance to study the characteristics and breakdown mechanism of air discharge in the condition of low air pressure.Based on the theory of gas discharge,the influence of air pressure,gap distance and voltage type is discussed,the development process and external characteristics of discharge plasma channel are studied,and the reasons for the formation of external characteristics of discharge channels are explained.There are some breakthroughs in the length of air pressure condition and discharge gap,and the results provide reference for air discharge characteristics of low pressure long clearance.