Hydrophobicity evaluation of polymer insulator using surface discharge characteristics

With the spread application of polymer insulators in UHV and EHV transmission lines, the decrease of hydrophobicity becomes one of prominent factors to affect the stability and reliability of power system. Recently, dynamic dropping test (DDT) has been employed to hydrophobicity evaluation, which has proven the occurrence of different discharge phenomena in relation to the hydrophobicity variation. However, limited analysis of discharge characteristics is carried out for the hydrophobicity evaluation by using DDT. In this paper, based on DDT method, the characterization of surface discharges, including the discharge magnitude, pulse number, adjacent discharge magnitude and adjacent time interval, have been analyzed to for the hydrophobicity evaluation. It is found that with the decrease of hydrophobicity, these characteristics of surface discharges apparently show the increasing tendency. The results obtained can indicate that the characterization of surface discharge in DDT method can be utilized to the hydrophobicity evaluation.