Space charge dynamics at the physical interface in oil-paper insulation under DC voltage

• Published in: IEEE transactions on dielectrics and electrical insulation 2015-06, Vol.22 (3), p.1739-1746
• Main Authors: Huang, Meng, Zhou, Yuanxiang, Chen, Weijiang, Lu, Licheng, Jin, Fubao, Huang, Jianwen
• Format: Article
• Language: English
• Subjects: Anodes; Cathodes; Dielectrics; Electric fields; Insulation; interface; oil-paper insulation; polarity reversal voltage; pulsed electroacoustic method; Simulation; Space charge
• ISSN: 1070-9878; 1558-4135
• DOI: 10.1109/TDEI.2015.7116372

Space charge has received much attention recently because an understanding of space charge in oil-paper insulation is useful for the design of converter transformers. This paper presents a study of space charge dynamics at the physical interface using the pulsed electroacoustic (PEA) method. After sample inversion, space charge in the vicinity of semiconductor electrode could be clearly observed when the sample is under depolarization. When an unexposed sample was placed next to a previously polarized one, negative charge appeared at the dielectric interface. These results indicated that there were other reasons in addition to acoustic loss that led to space charge distribution distortion. As regards the dielectric interface, it was found that an electrical double layer was formed at the interface, and the space charge sign was dependent upon the polarity of applied voltage. Space charge behavior at the interface depended on several aspects of the status of the interface, and during voltage polarity reversal, the interface was a weak point of the insulation.