期刊名称：International Journal on Electrical Engineering and Informatics
印刷版ISSN：2085-6830
出版年度：2018
卷号：10
期号：2
页码：220-231
DOI：10.15676/ijeei.2018.10.2.2
出版社：School of Electrical Engineering and Informatics
摘要：An accelerated aging test is an important test to assess a long time performance ofan insulation system. This paper deals with the investigation results on thermally aged naturalesters insulating liquid used for transformator. Two kinds of monoesters, palm fatty acid ester(PFAE) and stearic/oleic/linoleic acids methyl esters (M182), and one tri-ester, Envirotemp(FR3), were aged at the temperature of 120 oC for 60 days. An as-received oil was used as asample for aging test, so that the presence of a limited amount of air, and thus oxygen, in oilsample could not be avoided. The important properties like appearance, moisture content,acid value, volume resistivity, and breakdown voltage are evaluated at each 15 days interval.Experiment on mineral oil under the same condition was also conducted for comparison. Itwas observed that the color of the FR3 was changed from light-green to dark-green. PFAE,M182 and mineral oils which were initially transparent became yellow-green, light yellowand brown, respectively. A sludge formation was observed in the mineral oil, whereas theincrease in acidity was found in the PFAE and M182 oils. The moisture content of agedPFAE and M182 oils decreased whereas that of aged FR3 and mineral oils increased. Thevolume resistivity of all tested oils decreased with aging time, whereas their breakdownvoltage showed a different behaviours. The breakdown voltage of M182 and mineral oilsincreased and decreased, respectively, whereas that of PFAE and FR3 relatively unchanged.
