Characteristics of UHF and Pressure Changes Under Insulation Defects in Oil-Paper Insulation Bushing

Transformer bushing is important insulation equipment outside the transformer. If there are insulation defects for a long time, it may cause the risk of safety accidents such as fire and explosion. In view of the inadequacies of the existing insulation detection technology of oil-paper insulating bushing, the UHF and pressure variation characteristics of oil-paper insulating bushing during the development of partial discharge defects are studied in this paper. The UHF and pressure variation characteristics and their correlation characteristics of different severity partial discharge in the development process of oil-paper insulated bushing are obtained through the discharge insulation defect simulation platform. The results show that the pressure rise curve shows a trend of fluctuating around 0 at first and then rising, and the fluctuation duration is inversely proportional to the severity. The pressure increment within 120 min is proportional to the severity. After the voltage is applied for a long time, the model with weak severity will develop to discharge “self-extinguishing”, while the UHF amplitude of the model with strong severity will rise again, and the pressure will rise again and develop to breakdown when it is stable.