低温下水分含量对天然酯绝缘油介电特性的影响

Effect of Water Content on Dielectric Properties of Natural Ester Insulating Oil at Low Temperature

为研究低温下水分含量对天然酯绝缘油介电特性的影响,搭建了低温试验平台,在-15~5℃温度区间内对不同水分含量天然酯绝缘油进行交流击穿试验、直流击穿试验和工频介电特性测量。结果表明:低温下天然酯绝缘油的击穿电压随着温度的降低呈现出先减小后增大的趋势,其中直流击穿电压小于交流击穿电压,随着水分含量的增加,交、直流特性曲线逐渐接近;低温条件下水分的形态变化会影响天然酯绝缘油的介质损耗因数,随着温度的降低,天然酯绝缘油的介质损耗因数呈现先增大后减小的趋势,并在-5~0℃内出现极大值,但在低含水量时温度对其介质损耗因数影响不大,水分的存在会增大天然酯绝缘油的介电常数,而温度变化对天然酯绝缘油的介电常数影响不大。

In order to study the effect of water content on the dielectric properties of natural ester oils at low temperature,we established a low temperatures experimental system,then the natural ester insulating oils with different water content were conducted AC breakdown test,DC breakdown test,and power frequency dielectric properties measurement from-15℃ to 5℃.The results show that with the decrease of temperature,the breakdown voltage of the natural ester insulating oil decreases at first and then increases,and its DC breakdown voltage is lower than AC breakdown voltage.With the increase of water content,the AC/DC characteristic curves are getting closer.The dielectric loss factor of the natural ester insulating oil is affected by the variation of water morphology at low temperature.With the decrease of temperature,the dielectric loss factor of the natural ester insulating oil increases at first and then decreases,and its maximum value appears at-5-0℃,but the temperature has little effect on the dielectric loss factor under low water content.The existence of water will increase the dielectric constant of the natural ester insulating oil,while the temperature change has little effect on the dielectric constant.