固体开关柜环氧树脂材料绝缘特性研究

Insulation Characteristics of Epoxy Resin Material for Solid Switchgear

固体开关柜在外部因素作用下长时间运行会出现绝缘劣化现象,实现开关柜的可靠运行和绝缘状态监测是现阶段亟待解决的问题。对一种12 kV电压等级的三工位固封极柱三维建模后进行电场分布计算,得到进线套管、出线套管、真空灭弧室、隔离开关外部环氧树脂材料的最大场强分别为1.55、1.57、0.04、0.07 kV/mm,即开关柜长期运行条件下环氧树脂材料主绝缘应力点位于进出线套管。依据该部位结构特点设计了一种"同轴圆柱"电极结构的等效固封试件,选取5个初始绝缘参数相近的试件进行加速电老化试验,重点研究绝缘参数与老化时间的关系。结果表明:试件的局部放电发展过程分为潜伏期、发展期、劣化期3个阶段,对该类型设备的运行维护可提供一定参考;试件的介质损耗因数(tanδ)与老化时间具有很好的线性关系,通过方程拟合得到设定使用年限对应的最大tanδ,此值可作为考量产品电气绝缘寿命的依据。

The insulation of solid switchgear will deteriorate in long-term operation under the influence of external factors. It is a main problem to be solved to realize the reliable operation and insulation state monitoring of solid switchgear at this stage. A three-dimensional model of 12 k V three-position embedded pole was established, and its electric field distribution was calculated. It was found that the maximum electric filed strength of the external epoxy resin materials of entrance bushing, lead-out bushing, vacuum interrupter, and disconnecting switch is 1.55, 1.57, 0.04, 0.07 kV/mm, respectively, which indicate the stress point of epoxy resin main insulation was located at entrance and lead-out bushings in the long-term operation of switchgear. According to the structural characteristics of this part, an equivalent embedded specimen with'coaxial cylinder'electrode structure was designed. Five specimens with similar initial insulation parameters were conducted accelerated ageing tests, and the relationship between insulation parameters and ageing time was mainly studied. The results show that the partial discharge of specimens can be divided into three stages, including incubation period, development period, and deterioration period, which can provide some reference for the operation and maintenance of this type equipment. The dielectric loss factor(tanδ) of the specimen has good linear relationship with ageing time. The tanδ corresponding to setting service life, which is obtained by equation fitting, can be used as basis to consider the electrical insulation life of products.