Ageing studies on transmission line glass insulators using dielectric dissipation factor test

This paper reports an investigation carried out in the laboratory on units of transmission line glass insulator samples using Dielectric Dissipation Factor (DDF) Test. Two groups of insulator samples were used in the study. The first group comprised of naturally field-aged insulators with different ageing periods→30, 20, 15, and >;10 years from a 132 kV transmission line which have exhibited different degree of corrosion. The second group of insulator samples were relatively new insulator samples which have undergone accelerated ageing under acid rain condition. The results revealed a strong correlation between the loss angles with the degree of corrosion of the naturally field-aged insulators and exposure time of the artificially aged insulator samples under acid rain. Thus this finding suggests the viability of using DDF to diagnose transmission line insulators which hitherto such non-destructive diagnostic test was used on high voltage cables.