| Vegetable insulating oil is a new biodegradable dielectric fluid with a high flash point & fire point which has been successfully used to distribution transformer. Because of the difference of physical and chemical properties between the vegetable insulating oil and mineral insulating oil, theorical and experimental research on properties of vegetable oil-paper impregnation is needed. During the process of ageing, the hydrolysis dynamic properties of vegetable oil-paper insulation are more complex than mineral insulating oil. In the meantime, along with the development of nanotechnology, the research on nano-modification of insulating oil has become a new topic in the field engineering dielectric field. Therefore, based on large number of papers, the author do research on the impregnation mechanism, hydrolysis dynamic properties of vegetable oil-paper insulation, the preparation and breakdown characteristic of nano-modified vegetable insulating oil and so on. The research results in this paper as follows:①Based on the law of poiseuille, the research analyze oil-paper impregnation mechanism, discuss the test and calculate method of vegetable oil-paper impregnation, and present the method of testing capillary gravity of insulating paper in insulating oil by the contact angle meter. Results show that the measurement precision of the capillary gravity of insulating paper measured by the contact angle meter is good. The results of calculation and experimental from the model of vegetable oil-paper impregnation are same. Results of vegetable oil-paper impregnation model and experimental results are same.②The hydrolysis dynamic data of vegetable oil under various temperature, time period and water-oil ratio is measured systematically, the test condition and method of vegetable insulating oil experiment in hydrolysis is put forward. According to the test results of hydrolysis rate, author calculate the activation energy of the hydrolysis of the vegetable insulating oil, put forward and eatablish hydrolytic kinetic equation of vegetable insulating oil; The dielectric properties of vegetable insulating oil such as power frequency breakdown voltage, dielectric spectroscopy and volume resistivity is tested under different hydrolysis phase. The influence of acid products affecting dielectric properties is also analyzed.③The dynamic hydrolysis properties of vegetable oil-paper insulation under thermal aging are studied, design the aging testing equipment and testing method of vegetable oil-paper insulation with trace moisture is designed; And the influence of copperon hydrolysis properties of the vegetable oil-paper insulation is also studied. The research analyzes the variation of properties during hydrolysis process. These variation quantities include the moisture in oil and paper, breakdown voltage, acid value, furfural concentration and polymerization degree of insulating paper. According to the acid value of insulating oil during vegetable oil-paper insulation aging, the research calculates the activation energy of the insulation hydrolysis reaction and establishes the reaction kinetics equation for hydrolysis.④The surface of Fe3O4 nano-particles is modified by coating with oleic acid. The research prepare the blending particles that blend with the vegetable insulating oil and Fe3O4 nano-particles; The characters of original nano-particles and the modified ones are tested by laser particle size analyzer, transmission electron microscopy, attenuated total reflection-Fourier transform infrared, thermal gravimetric analysis, which test the particle size distribution, surface morphology, oleic acid coating effect and the stability of Fe3O4 nano-particles in insulating vegetable oil .Results show that the surface of oleic acid and the Fe3O4 nano-particles are both physical surface coated and chemically bonded.⑤The physical, chemical and electrical properties of nano-modified insulating vegetable oil is tested. The research focuses on that the failure behavior of nano-modified insulating vegetable oil under power frequency and lightning impulse voltage. The frequency-variation laws of relative dielectric constant, dielectric loss tangent and volume resistivity of oil is tested by dielectric spectrometer. Combining theories of space charge distribution with theories of polarization of nano-particles in electric field, the mechanism improving properties of nano-modified insulating vegetable oil is studied. The result shows that the dielectric properties of nano-modified insulating vegetable oil are improved.This work reveal the impregnation and hydrolysis properties of vegetable insulating oil, it proves that the power frequency and impulse electrical strength of vegetable insulating oil is improved by adding surface modified Fe3O4 nano-particles. This work is of important value in the application of vegetable insulating oil and vegetable oil-based insulating nanofluid.
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