Research on aging characteristics of twisted pair based on dielectric loss under high frequency pulse voltage

This paper conducted experiment research on enameled wire used in inter-turn insulation of JD117 inverter-fed motor and focused on twisted pairs as test object. Bipolar pulse voltage aging test was conducted under various frequency and time; dielectric frequency and temperature spectra of specimen were measured and analyzed; combining with Scanning Electrical Microscope (SEM), the influence of different aging conditions on surface morphology were researched. The experiment results reveal that with the aging degree deepening, through analyzing frequency spectrum of tan delta, its peak value can be used to judge the insulation condition. There exists significant difference of surface morphology of twisted pair between non-aging and aging. That difference becomes increasingly evident with the deepening of aging degree.