To effectively predict insulator contamination levels

improve operational safety and reliability of catenary

an on-line monitoring catenary insulator leakage current device is developed

which is based on ARM. The device judges whether insulators should be cleaned by the contamination levels

which is predicted by leakage current and ambient humidity. Select a composite insulators of FQBJ—25 /8—760P as research object

carry out artificial pollution test using on-line monitoring device

under satur-ated air humidity. Fitting relation curves of contamination level and leakage current using experimental datas

and provide guidance to confirm alarm value of catenary insulator leakage current on-line monitoring device. Based on three-stage idea of pollution flashover

propose safe operating area

filth cleaning area and danger area of catenary insulator.