Research on the Interrelation between Temperature Distribution and Dry Band on Wet Contaminated Insulators

Abstract

In this paper, the interrelation between temperature distribution and dry band on wet contaminated insulators is studied by theoretical analysis, numerical simulation, and a high-voltage artificial contamination experiment. The influences of the composition of the contaminant and the relative humidity of the environment on the moisture absorption of the contamination layer are studied. It is indicated that the critical relative humidity (CRH) of the soluble mixture in the contamination layer decreases with the increase of the variety of soluble substances. This can be considered as a previously neglected reason for the inconsistency between the result of an artificial contamination test and that of a natural contamination test. Furthermore, the influences of the maximum temperature, wind speed, altitude, relative humidity, and the composition of the contamination on the water evaporation rate of the contaminated layer are also studied. The formation of dry band is predicted by studying the law of water transport in the contamination layer. The influence of the location, width, drying degree, and quantity of dry bands on the insulator surface temperature are studied by numerical simulation. An infrared thermal imager and ultraviolet camera are adopted to measure the temperature distribution and the discharge phenomenon on the insulator surface separately, which verifies the above numerical simulation. The study results deepen the research on the moisture absorption characteristics, the law of temperature distribution, the formation of dry bands, and the influence of dry bands on the temperature distribution of wet contaminated insulators.