Evaluation of the hydrophobicity of composite insulators based on on-line detection

This paper introduces an on-line hydrophobicity detection technique and its application. Firstly, a new hydrophobicity classification estimation method, named improved shape factor method, was brought forward based on spray method and digital image processing technique. Also, an on-line hydrophobicity detection apparatus was designed, which includes an automatic electric sprayer, a mini digital video camera, and hydrophobicity analyzing software. Secondly, with the apparatus, field investigations on hydrophobicity of composite insulators in service were made in a heavily polluted area of north China for half and a year. A seasonal variation of hydrophobicity was found through field test, which was also confirmed by outdoor simulation test. Therefore, a new method was proposed to evaluate the dynamic performance of hydrophobicity, by online characterize hydrophobicity of the composite insulators in winter and summer, respectively. Thirdly, with SEM and ATR-FTIR techniques, the mechanism of hydrophobic decrease was analyzed, and the significant influence of pollution on hydrophobic decrease in different seasons was pointed out. Finally, the maintenance method of composite insulators based on on-line hydrophobicity detection technology was discussed.