The equivalent investigation of natural contamination and artificial contamination test

In order to study how the factors (NSDD, distribution of nastiness, components of salt, etc) influenced the flashover characteristics of insulators, the artificial contamination tests were carried out for composite insulators in the conditions of different nonsoluble deposit density (NSDD) and different distribution of nastiness and different components of salt in the area of high-altitude Kunming. The paper concludes that the relationship between the coefficient of modifiability of NSDD and NSDD was a negative power function in the condition of equivalent salt deposit density (ESDD) remained constant and the NSDD of insulators was no more than 1.0 mg/cm²; the flashover voltage increased with the degree of ununiform pollution distributing in the condition of NSDD remains constant; the relationship between the coefficient of modifiability of the different components and the proportion of CaSO₄ was an exponent function in the condition of ESDD remained constant. These results would be useful in calculating the DC flashover voltage of composite insulators in the condition of natural contamination, and can also be treated as basis for outdoor insulator selection of transmission lines.