Effects of natural contamination components on the surface conductivity under saturated moisture

The natural contamination components vary in different areas. NaCl is the major soluble salt on the surface of insulators in coastal areas. In contrast, the proportion of CaSO4in inland areas is greater, which makes pollution flashover voltage of insulators have large scatter. As a result, the relationship between ESDD and pollution flashover voltage is unclear. However, in the artificial contamination pollution flashover experiments, NaCl is often utilized as the single soluble salt in the contamination, and there is a clear negative exponential relationship between the pollution flashover voltage and the SDD. In this paper, the relationship among ESDD, contamination components and surface conductivity of insulators under saturated moisture is analyzed. On this basis, the ratio of surface conductivity to ESDD is proposed to describe the difference of soluble salt components in natural contamination. Experimental results indicate that the ratio of surface conductivity of the polluted insulators under saturated moisture to ESDD is in the range of 14-866. This ratio is inversely proportional to the proportion of CaSO4in the soluble salts of the natural contamination. If two of the three parameters, namely, the surface conductivity, ESDD, and contamination components, are measured, the remaining one can be calculated. The ratio of surface conductivity to ESDD can be utilized as a parameter to describe the components of natural contamination.