For a long period

something was introduced that there was a lack of effective and convenient methods for on-line monitoring insulation of high-voltage transmission lines composite insulators. Lacking the data of the composite insulators’ working state becomes a threat to the power grid operating security. This paper summarizes anarchical investigations and operating experiences including the electric leakage marks and the electrolytic corrosion damage processes of the composite insulators’ housing material

and the insulators’ wear-out faults. It confirms the main characteristic data and preliminary stage criterion for on-line monitoring insulation of composite insulators

and puts forward an integrated design idea and a system solution for the on-line monitoring terminals. It acquires preliminary research achievements on on-line monitoring insulation of composite insulators.