法兰进水结冰引起的瓷套开裂研究

Porcelain Insulator Cracking Caused by Flange Icing

为明确超高压500 kV某变电站运行电容式电压互感器瓷套开裂原因。采用宏观检查、超声波检测、尺寸检查、孔隙性试验、X射线光电子能谱分析等方法,从材料、结构和环境等角度研究了该瓷套开裂的原因,并利用有限元计算对其进行了验证。发现法兰盘防水胶脱开,腔内存在积液痕迹,且胶装偏心。结果表明,防水胶脱开,雨水通过胶装面渗透在下法兰盘腔内积液,在低温状态下,胶装面贴合面中的积液结冰发生体膨胀是引起绝缘子开裂的主因;次因是下节(即故障件)瓷件下法兰胶装偏心,偏心引起了孔中心偏移,使其在结冰膨胀状态下产生了一个极大的剪切力,该应力在绝缘子受力薄弱处即上侧法兰结合部位(俗称颈部)得到了释放,从而导致了事故的发生。

In order to clarify the reasons of porcelain insulator cracking of capacitor voltage transformer in an ultra-high voltage 500 kV substation, tudi from the aspects of material, and by means of macroscopic inspection, dimensional inspection, ultrasonic inspection, red absorption test and X-ray photoelectron spectroscopy analysis, and verified by finite element calculationt was found that the waterproof glue was off, there were traces of fluid in the cavity and the flange rubber was acentric. The results showed that the main reason for the insulator cracking was that the water drops off and penetrating the liquid in the lower flange cavity through the adhesive surface, and the liquid and expanded in the adhesive surface at low temperature.The secondary reason was that the flange glue assembly of the lower section(the fault part) porcelain part was, which caused the deviation of the hole center and produced a great shear force under the freezing expansion state. The stress was released at the weak point of the insulator(commonly known as the neck), thus leading the accident.