In view of the difficulty to effectively analyze the polarization relaxation response speed of the common recovery voltage characteristics,a relaxation slope was proposed to research into the dielectric characteristics of the insulating medium and the insulation state of the transformer.The internal connec-tion between the relaxation slope polarization spectrum and the aging of transformer insulation medium was theoretically analyzed,and an extended Debye equivalent circuit model established to study the influ-ence of transformer equivalent circuit parameter variations on relaxation slope polarization spectrum.The theory and simulation results were verified by the measured data of multiple transformers and the results showed that the relaxation slope polarization spectrum could effectively reflect the insulation aging state of the transformer.The more serious insulation aging state of the transformer,the greater peak of the relaxation slope polarization spectrum,and the insulation aging of the transformer mainly affected the front end of the relaxation slope polarization spectrum(tc<10 s);when relaxation slope k≥20,its insu-lation state was in a serious aging state.
transformeroil paper insulationreturn voltage characteristic quantityrelaxation slopeequivalent circuit
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