含有裂纹缺陷的GIS盆式绝缘子的静力特性及其影响因素分析

Static Force Characteristics and Influencing Factors Analysis of GIS Basin-type Insulator with Cracks

GIS盆式绝缘子的静力特性问题是盆式绝缘子制造和运维中的关键问题。文中建立了252 kV正常或含有缺陷盆式绝缘子的三维模型,采用有限元法计算了盆式绝缘子在不同气室压力、不同裂纹大小和不同母线温度下应力分布特性。研究结果表明,当盆式绝缘子两侧气室压力均为0.4 MPa时,最大应力为1.3 MPa,最大应力点为外法兰和绝缘子本体交界面附近。若下表面气室压力为0.1 MPa时,最大应力为12.3 MPa;若上表面气室压力为0.1 MPa时,最大应力为10.9 MPa,但均未超过环氧树脂的屈服强度40 MPa。当绝缘子存在裂纹时,裂纹附近会出现应力集中,裂纹端部比中间部分应力变化大。当裂纹深度为厚度1/4时,裂纹处最大应力为1.3 MPa;当裂纹深度为厚度3/4时,裂纹处最大应力达到2.3 MPa。绝缘子上下表面压力不同会进一步加剧裂纹处的应力集中。当母线温度升高时,绝缘子承受应力增加,最大应力点为母线与绝缘子本体交界面。

The static force characteristic of GIS basin-type insulator is the key problem in its manufacture,operation and maintenance.Three dimensional models of 252 kV normal or defective insulators are established in this paper,and stress distributions of insulators are calculated based on the finite element method under different chamber pressures,different crack sizes and different bus temperatures.It is shown that maximum stress is 1.3 MPa and maximum stress appears in the interface of outward flange and insulator bulk when the chamber pressures of both surfaces are0.4 MPa.If the chamber pressures of lower surfaces are 0.1 MPa,maximum stresses is 12.3 MPa.If the chamber pressures of upper surfaces are 0.1 MPa,maximum stresses is 10.9 MPa,but maximum stresses mention above are below the yield strength of epoxy.While there are cracks in basin-type insulators,stress concentrations occur.The stresses of the endpoint of crack change more than those of the midpoint.When the depth of crack is a quarter of the thickness,maximum stresses of crack is 1.3 MPa.When the depth of crack is three quarters of the thickness,maximum stresses of crack is 2.3 MPa.And if the chamber pressures of both surfaces are different,stress concentration of crack will increase by a large margin.With the increase in the bus temperature the stresses are increased,and the maximum stress appears in the interface of the bus and insulator bulk.