期刊名称：International Journal on Electrical Engineering and Informatics
印刷版ISSN：2085-6830
出版年度：2013
卷号：5
期号：2
出版社：School of Electrical Engineering and Informatics
摘要：This paper presents an experimental study on long time range breakdown of Low Density Polyethylene (LDPE) under very high dc applied fields (Emean) of 2.0 MV/cm or 3.0 MV/cm. Breakdown time lag and space charge distribution are simultaneously measured for a 200-µm-thick LDPE sheet with positive-semicon and negative-evaporated Al electrodes. A voltage is applied to the sheet until the dc breakdown occurs. 20 samples are tested for both the applied voltages. It should be remarked that 50 % survivor probability T50 , corresponding to time in which breakdown occurs for 10 samples out of 20, is 70 min for 40 kV, whereas it is 90 min for 60 kV. Results of the space charge measurement by pulsed electro acoustic (PEA) method indicates that a large number of positive charges are injected from the semicon-anode and they are accumulated in the bulk of LDPE, so that field distribution in LDPE is strongly distorted. The maximum field strength Emax(t) in LDPE after the space charge penetration for 60 kV becomes higher than that for 40 kV. However, the distortion ratio Emax(t) / Emean under 40 kV is higher than that under 60 kV. This is because the positive charges packet produced by 40 kV penetrates into deeper area of the bulk as compared with that by 60 kV.
关键词：Space charge; pulsed electro acoustic method; low density polyethylene;breakdown time lag
