天然酯-纸绝缘与矿物油-纸绝缘的热老化及工频击穿特性对比

天然酯具有良好的电气、抗老化和环保等优越性能,被认为是矿物绝缘油的良好替代品。研究天然酯-纸绝缘的热老化产物生成规律和工频击穿特性,对于确保天然酯在变压器中的安全应用具有重要的理论和实际意义。为此,以天然酯和矿物油分别与普通绝缘纸组成油纸绝缘试品,在110°C和130°C下分别进行了加速热老化试验,对比分析了两种绝缘组合的老化产物生成规律和工频击穿特性。结果表明:在老化过程中天然酯中水分质量分数比矿物油高1个数量级;130°C老化时天然酯浸纸的水分质量分数高于矿物油浸纸,110°C时却相反;两种油的酸值随老化时间增加均增大,老化温度越高酸值越大,且天然酯酸值高于矿物油,110°C时天然酯浸纸中酸值也高于矿物油浸纸;虽然在热老化过程中,天然酯及其油浸纸的水分、酸值要高于矿物油及其油浸纸,但天然酯-纸绝缘比矿物油-纸绝缘具有更高的工频击穿电压。

Comparative Analyses of Thermal Aging and Power Frequency Breakdown Characteristics Between Natural Ester-paper Insulation and Mineral Oil-paper Insulation

Natural ester is considered as a promising substitute for mineral oil because of its excellent electrical performance,high anti-aging ability and environmental friendly feature.It is of great theoretical and practical values to study thermal aging products and power frequency breakdown characteristics of natural-ester-immersed insulation paper,ensuring the safe application in transformers.We prepared two kinds of oil-paper insulation samples with common insulation paper and insulation oil,namely,natural ester and mineral oil,respectively.Accelerated aging experiments were performed under the 110°C and 130°C to analyze the generation principle of aging products and the power frequency breakdown characteristics for these kinds of oil-paper insulation samples.The results reveal that,during the aging process,the moisture content of natural ester is ten times that of mineral-oil-paper insulation;at the aging temperature of 130°C,natural-ester-immersed paper has a high moisture content than mineral-oil-immersed paper,while it is to the contrary at the aging temperature of 110°C;the acidity of both kinds of oil increases with aging time,meanwhile,the higher aging temperature is,the more the acidity becomes;furthermore,natural ester has higher acidity than mineral oil,at the aging temperature of 110°C,the acidity of natural-ester-immersed paper is higher than that of mineral-oil-immersed paper;although the natural ester and the corresponding oil-immersed paper present high values of moisture content and acidity than mineral oil and the corresponding paper,the natural-ester-paper insulation exhibits a higher power frequency breakdown voltage compared with mineral-oil-paper insulation.