Study On Characteristics Of Air GAP Defect Of Basin Insulators In GIS Considering Temperature

The continuous improvement of voltage level requires higher insulation performance of electrical equipment.At present,high voltage switch mainly adopts SF₆gas with high insulation strength and high arc extinguishing ability as insulation medium,such as circuit breaker,isolation switch and so on.The gas insulated metal sealing assembly?GIS?is assembled by a large number of intervals,and the gas chambers are separated by the epoxy resin basin insulators.With the large amount of transportation and long run of GIS,the accidents caused by various defects are still inevitable.In basin insulator,partial discharge caused by air gap defect develops to a large number of failures,which brings huge economic losses and security threats.However,most of the researches are focused on the air gap electric field at room temperature.There are few studies under the operation temperature of electrical equipment.Firstly,this paper introduces the current research status of air gap discharge.It is believed that the three-capacitor model used today ignores the influence of temperature on the discharge characteristics,and the finite element analysis method which has been widely used in recent years can consider many influential factors,and now the finite element software plays an important role in various fields and proves its strong strength.The gas discharge phenomenon of higher air pressure and slightly longer clearance is required for ultra/high pressure,the flow injection theory is required.In this paper,the flow theory of air gap discharge is studied,the influence of insulating medium on the discharge is considered,and the charge attenuation and generation of the dielectric barrier between electrodes are analyzed.The ionization coefficient is related to the pressure by the analysis of the electron source,and the pressure of the gas is often related to the temperature.In addition,the uniform electric field in spherical or ellipsoid is calculated by the polarization theory,which can be seen that the electric field in the air gap is obviously higher than that of the insulating material,and the partial discharge is easy to occur,even causes the accident.The electrical properties of insulation in different temperatures are often different,and it is often overlooked in the simulation,especially when it's too big,and it's very easy to create the simulation results that are very different from the results of the experiment.In this paper,the dielectric constant and dielectric loss characteristics of epoxy resin in temperature change are studied,and the curve of dielectric constant with temperature change is obtained.In addition,the voltage difference between the air and the SF₆ is made by the method of the temperature change,which is the method of calculating the voltage in the temperature change in the insulator.The breakdown voltage of SF₆ is also deduced.It use that finite element method to build the model of basin-type insulator in ANSYS.Based on the model,the electric field of the insulator at normal temperature was simulated.And the temperature simulation results were divided into three parts,which were divided into three parts to give different dielectric constants,and the different sizes of air gaps were located in different positions to study the change of electric field intensity in the vicinity of the air gap and the insulator.