基于电、热、酸复合应力下复合绝缘子芯棒老化特性研究

Aging Characteristics of FRP Core Rods in Composite Insulators Through Electric,Acid and Thermal Combined Stresses

酥朽断裂是如今高压输电线路中复合绝缘子的新型机械故障,现有的研究均集中于酥朽断裂绝缘子芯棒的老化过程和理化特性,但很少有研究在实验室试验中模拟这种现象。建立了一种具有高温,酸腐蚀和高电场强度等多种老化条件的人工加速老化平台,一定程度上模拟了酥朽断裂绝缘子芯棒的典型特征。结果表明,当施加电压数小时后,使用热红外成像仪检测发现温度明显升高。与单一老化应力相比,芯棒样片在多应力条件下的温度高达61℃。此外,采用扫描电子显微镜(SEM),傅立叶变换红外(FTIR)光谱,X射线光电子能谱(XPS)和热重分析(TGA)方法研究了芯棒样片理化特性的变化,并进一步研究了老化过程中发生的反应和不同老化因素之间的作用机制。结果表明,环氧树脂基体被水和硝酸侵蚀。在高电场的存在下,环氧树脂基体进一步降解并蒸发,环氧树脂和玻璃纤维之间的界面分离,伴随着离子交换和水解过程。随着芯棒样片进一步劣化,试样出现明显的碳化通道和电蚀穿孔。与酥朽断裂绝缘子芯棒相比,人工加速老化样品在理化特性上表现出相似的变化趋势,研究结果可为理解复合绝缘子实际运行工况下的多场耦合老化过程提供参考。

The decay-like fracture is a new type of composite insulator mechanical failure in high voltage transmission lines in several countries.Recent studies have focused on the aging process and physicochemical properties of the degradation area in the broken insulator,but few research simulated and represented the phenomenon in laboratory experiment.In this paper,an artificial accelerated aging platform of Fiber Reinforced Plastic(FRP)core rod with various aging conditions including high temperature,acid corrosion and high electric field strength was built.And the typical degradation characteristic of FRP core rods in decay-like fracture insulators was simulated and reappeared.The thermal infrared imager was used to detect the temperature rise when the AC voltage was applied for several hours.The results showed that the rising temperature of the FRP specimens under multiple stresses was significantly increased up to 61℃(177%)compared with the specimen under single aging stress(22℃).Moreover,Scanning Electron Microscope(SEM),Fourier Transform Infrared(FTIR)Spectroscopy,X-ray Photoelectron Spectroscopy(XPS)and Thermal Gravimetric Analysis(TGA)methods were applied to study the physicochemical properties of the aging FRP specimen and the reaction occurred in the degradation process and the influence mechanism among different aging factors.The results showed that the epoxy resin matrix was eroded by water and nitric acid.In the presence of high electric field,the epoxy resin matrix was further degraded and evaporated.Then the interface between the epoxy resin and the glass fiber separated and developed,accompanied with ion-exchange and hydrolysis process.With the development of the degradation process of FRP core rod,obvious carbonized channel can be detected.Finally,electric erosion puncture occurred and breakdown happened.Compared with the FRP core rod extracted from the decay-like fractured composite insulators,the artificial accelerated aging sample showed the similar change trend on physicochemical properties.This study result can provide reference for the FRP core rod degradation mechanism and life predicting of high voltage composite insulators or other actual operation environment.