A Low-Cost Evaluation and Correction Method for the Soluble Salt Components of the Insulator Contamination Layer

Presently, equivalent salt deposit density (ESDD) is widely used by scientists and utility engineers to describe the site pollution severity due to its simple measurement procedure. When the contaminants are naturally accumulated on the insulator surface, some slightly soluble salts are only partially dissolved under saturated moisture condition. However, due to the large water consumption in the ESDD measurement process, these slightly soluble salts can be totally dissolved. Therefore, the measured ESDD may be higher than the actual pollution severity on the insulator surface. Thus, if using the measured ESDD to evaluate the flashover voltage of insulators in artificial pollution tests, the obtained results may be different from that of naturally contaminated insulators. This paper studied the dissolution amounts of highly and slightly soluble salts in the contamination layer by the ESDD measurement and compared them with a method proposed in this paper. The proposed method measures the surface conductivity of insulator under actual saturated moisture condition and can be used to correct the soluble salt components of natural contamination. Based on this method, a simple and novel device were also developed. The method proposed and device developed in this paper will be particularly useful for the selection and the design of insulators used in transmission lines.