Analysis of Dielectric Properties and Breakdown Characteristics of Vegetable Insulating Oil with Modified by ZnO Nanoparticles

In view of the higher requirements of electrical, physical and chemical properties of vegetable insulating oil in large power transformers, the method of improving insulation characteristics of vegetable insulating oil by using nanoparticles has become a research hotspot at home and abroad. In this paper, the preparation, surface modification of ZnO nanoparticles and the preparation process of the vegetable insulating oil based ZnO nanofluids (NF) were studied. The effects of different ZnO nanoparticles concentration on dielectric properties and breakdown characteristics of vegetable insulating oil were analyzed. The results shown that the power frequency breakdown voltage of ZnO NF similar to linear increased with the increasing of nanoparticles concentration, the maximum increase was 30.17%. The positive and negative polarity breakdown voltage of lightning impulse shown a trend of first rise and then decrease, and the positive and negative breakdown voltage increased by 24.62% and 5.46%, respectively. Both the positive and negative lightning impulse breakdown time of ZnO NF increasing with the nanoparticles concentration, the max value were 18.94%, 35.76%, respectively. However, ZnO nanoparticles would increase the dielectric loss of vegetable insulating oil and reduce its volume resistivity.