The Research On Assessment Methods With Aging Of Composite Insulators In Zhongyuan Oil Field

Recently, composite insulators are increasingly used in power systems around the world. Now 60-70 percent of the newly produced insulators in the United States are composite insulators. In China, there are millions of composite insulators installed in 35kV-500kV power networks which are mostly used in the polluted areas. Composite insulators are easy to manufacture and are very light. The mechanical strength of composite insulators is also very high.Aging is a serious problem because composite insulators are made of organic materials. How to estimate the quality of the composite insulators is valuable to power network safety. As most power supply bureaus cannot carry out the pollution flash over test, this paper explores easy methods to detect the quality of composite insulators through experiment.Test on insulators having been in service for 3-5 years shows their good performance. This result may serve dance for other 35kV insulators. Little aging has less influence on the dry flashover and impulse flashover voltage of composite insulators. It is proposed to measure the magnitude and shape of leakage current as they can provide important information of composite insulator quality. The increase of leakage current and surface resistance is caused by the change of microcosmic state of the surface of composite insulators, which can be detected by scanning electron microscope (SEM). Hydrophobicity is the proper characteristic of composite insulators which can be evaluated by contact angle and insulating resistance measurement and it can be classified by HC classification. The contact angle measuring result is related to the volume of water drop. HC classification is very simple, but the result is not sufficient for evaluating the whole insulator. The relationship of hydrophobicity and wet flashover voltage of composite insulators is also discussed in this paper.