Comparison of natural contamination accumulation characteristics between composite rod insulators and standard suspended insulator strings

In order to attain the pollution characteristics difference between composite rod insulators and standard disc‐type suspended insulator which is critical to the insulation selection of transmission line, pollution accumulated on composite rod insulators and standard form suspended insulators suspended in the same tower near typical pollution sources in Zhejiang province were tested, including the equivalent salt deposit density (ESDD) and the non‐soluble deposit density (NSDD). Also the factors caused the difference were analysed for the first time. It is shown that in Zhejiang area, the contamination on upper surface of composite insulators is more serious than that of standard form suspended insulators, and the situation is inverse on the lower surface; the entire shed value of ESDD and NSDD from composite insulator is 0.8, 1.27 times of the values from standard form suspended insulators, respectively. The contamination difference of upper surface and lower surface of the composite insulators is smaller than that of standard form suspended insulators. According to the analysis, the rainfall and PM10 concentration could notably effect the ESDD difference between composite insulators and standard form suspended insulators. With stronger rainfall and less PM10 concentration, the ESDD ration of composite insulators and standard form suspended insulators trend to be smaller.