Physics and chemistry analysis on composite insulators after operated

To obtain ageing conditions of composite insulators after being operated, six composite insulators of three manufacturers are selected to perform hydrophobicity test, Fourier infrared spectroscopic analysis, thermoanalysis, and scanning electron microscope (SEM) detection. The results indicate that, hydrophobic groups, Si-CH 3 and -CH 3, of silicone rubber surface are less than those of inner part. -OH group has not obvious rule between surface and inner. Hydrophobic groups, Si-CH 3 and -CH 3, can be used as indicator of hydrophobicity variation, but -OH can not be used for this purpose. The composition of surface and inner layers of new composite insulator is similar. The inorganic compound of surface and inner layers of operated insulator has not obvious rule. The high polymer of surface and inner decreases with time, and the mass of inner is more than that of surface layer. For low molecular weight compound, the mass of surface layer is more than that of inner layer. Operation time affects SEM result to some extent. The hydrophobic level of new composite insulators belongs to HC1, and the hydrophobic level of operated composite insulators belongs to HC2~HC3. Different sheds or different positions of composite insulator may have different hydrophobicity.