Effect of Moistures on Space Charge and Trap Level Characteristics of Oil-Impregnated Pressboards

IEEE Access

Xinlao Wei¹  Qingguo Chen¹  Yi Guan¹  Minghe Chi¹  Qian Wang¹  Jinfeng Zhang² 

[1] Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, School of Electrical and Electronics Engineering, Harbin University of Science and Technology, Harbin, China;School of Electrical Engineering and Automation, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China;

关键词: Oil-paper insulation;    space charge accumulation;    charge trap;    moisture;   

DOI  :  10.1109/ACCESS.2020.3024768

来源: DOAJ

【 摘 要 】

Oil-paper insulation as an irreplaceable insulation system in the electrical power transformer is inevitably suffering the water intrusion on working condition, which will make dielectric performance degraded and insulation aging accelerated. In high interest of explaining the deterioration effect of absorbing moisture on the dielectric properties of oil-paper insulation system and corresponding mechanism, the space charge and trap level characteristics are investigated for the specially prepared oil-impregnated pressboards with different moisture contents. The Pulsed Electro Acoustic and Isothermal Surface Potential Decay experiments are performed to test the space charge distributions and evaluate the trap level depths, respectively. It is indicated that the polarity of injected space charges is alternated with the decaying rate being raised when the absorbing moisture is aggravated in oil-impregnated pressboards. The charge carriers are more prone to be captured by the shallow-level traps that have been introduced by water permeation near pressboard surface than the intrinsic deep-level traps inside pressboard. The captured charge carries accounts for the significantly exacerbated space charge accumulation as manifested by the surface charges of oil-impregnated pressboards.

【 授权许可】

Unknown