Research on Liquefaction Electric Field Study of Composite Insulating Medium for 500 kV SF6 Circuit Breaker
In order to study the impact of SF6 gas liquefaction in composite insulator bushings on the internal electric field distribution,this paper analyzes the internal electric field by using the finite element method of current field.Based on the parameters of composite bushings in a certain project,a 3D solid model is established.It is assumed that droplets appeare in important parts for calculating the transient electric field at power frequency,and the overall electric field intensity distribution law and the electric field intensity distribution law around the droplets are obtained.It is found that the axisymmetric method is no longer suitable for the analysis of SF6 liquefaction.The results indicate that droplets will cause an increase in the nearby field intensity,and the larger the dielectric constant of the droplets,the higher the electric field intensity.The electric field intensity may increase up to three times the original field intensity as the droplet parameters change,and breakdown may occur when the dielectric constant of liquid SF6 is high and the SF6 filling pressure is low.Furthermore,liquefaction and discharge are most likely to occur on the ground potential shield,requiring additional heating measures or replacement of the filling gas with SF6-N2 gas.
SF6 circuit breakercomposite insulating bushingliquefactionfinite element methodelectric field distribution
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