Pressure and UHF Variation Characteristics of Oil-Paper Insulated Bushing Capacitor Core with Impurity Defect

Aim at the problem that the traditional detection technology of the oil-paper insulating sleeve is easy to cause negative pressure in the equipment, As well as the problem that the modification of the end shield endangers the long-term reliability of the end shield ground, In this paper, the characteristics of UHF and pressure variation during the development of partial discharge defects in oil-paper insulation bushing are studied. The UHF and pressure variation characteristics and their correlation characteristics of PD with different severity in the development process of the casing are obtained. The results show that at the initial stage of discharge, The pressure rising slope is proportional to the discharge quantity; When the pressure is continuously applied for a long time, the less severe model will develop to discharge “self-extinguishing”. The UHF amplitude of the more serious model will rise again and develop to breakdown, and the duration of each stage is inversely proportional to the voltage level; When the discharge quantity rises slightly, the average amplitude of UHF does not change significantly, but the pressure rises significantly. There is a good fit between the increase of pressure and the increase of discharge. It shows that the pressure can directly reflect the change of the discharge cumulative energy.