Mechanism of fracture related heating for 500-kV composite insulators in highly humid areas.

With the adoption of composite insulators in the field of high voltage transmission, it is essential to focus on its safety performance. Our study paid attention to the extensive heating within HV ending of 500-kV AC composite insulators in southern China with high level of humidity and proposed corresponding countermeasures. Via superficial examination, IR and UV test, interface quality inspection, chemical analysis and water absorption test and etc., we were able to study the defected insulators. According to our observation, insulators were slightly covered with pollutants and maintained superficial hydrophobic properties. The heating performance of HV ending of insulators was closely related to humidity as well as the type and site of loading voltage. We suggested that when exposed to high humidity, polarization of the molecules from water, polar groups of material and the interlayer resulted in the abnormal heating; on the other hand, when the environment humidity was low the heating was attributed to partial discharge. Consequently, we provided several solutions toward the issue according to our observations. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]