Influence of temperature difference on wetting characteristics of insulators

When polluted insulators get wet, the flashover voltage will decrease dangerously, threatening the stability of the power grid. It is known that moisture is a necessary condition for the pollution flashover accident, for a great deal of research has been carried out concerning the effect of humidity on the moisture of insulators. As the climate in the inland area is dry and the humidity is low, the pollution flashover accident tends to occur early in the morning, when condensation on the surface of the insulator is the most serious due to the temperature difference between the insulator and ambient air. In order to study the effect of temperature difference on pollution layer wetting process, and improve the accuracy of the condition assessment and flashover alarming, this paper analyzes the source, the existence form and the variation tendency of the water absorption of the polluted layers under the temperature difference based on the leakage current of insulators. In addition, for verifying the effects of the temperature difference during the wetting process of the pollution layers quantitatively, a series of laboratory tests have been performed in a multifunction artificial climate chamber. The results indicate that the water absorption of the polluted layer is directly proportional to the temperature difference under the medium humidity, which may provide some valuable reference for the on-line monitoring of insulator contamination in inland arid areas.