Study On The Compatibility Between Vegetable Insulating Oil And Insulation Materials In Oil Filled Transformer

Vegetable insulating oil is environment-friendly and fire-resistant liquid dielectricswith good insulation properties. Vegetable insulating oil has been used in distributiontransformers. As the physical and chemical properties of vegetable insulating oil aredifferent from those of mineral oil, it is necessary to study the physical, chemical andelectrical properties of different mixing ratio insulating oil. Insulating oil in operationtransformers is directly exposed to solid materials in transformers. The reactions takingplace between vegetable insulating oil and solid material is more complex than thatbetween mineral insulating oil and solid material, so it’s necessary to research on theinfluences between vegetable insulating oil and solid materials. With the wide spreadingapplication of vegetable insulating oil, more theoretical analysis and basic data are needto ensure the safe and stable operation of transformers. Consequently, the compatibilityof vegetable insulating oil and transformer inner materials were studied, and the maincontents are shown as follows:①The compatibility tests between vegetable insulating oil and mineral insulatingoil were designed, and the chemical, physical and electrical properties of insulating oilwere analyzed and compared. The influence the acid value, moisture and breakdownvoltages of insulating oil by different mixing ratio were studied. The aging parametersof insulating oil with different mixing ratios, such as acid value, moisture content andbreakdown voltage of oil were measured in the thermal aging tests. Experimental resultsindicate that the molecular composition of insulating oil have a great influence on thephysical, chemical and electrical properties of oil. The more of vegetable insulating oilin mixed insulating oil, the higher acid value and moisture content of oil is. Vegetableinsulating oil and mineral insulating oil has good compatibility in thermal aging tests.②The compatibility tests between vegetable insulating oil and insulation paperwere designed. The changing rules of thermal aging characteristics in vegetableinsulating oil influenced by insulation paper were obtained. The changing rules of DP,breakdown voltages and mechanical strength of insulation paper influenced byvegetable insulating oil were analyzed. Experimental results show that the insulationpaper may accelerate the aging rate of vegetable insulating oil and mineral insulating oil.Compared with mineral insulating oil, vegetable insulating oil could postpone the agingprocess of oil-impregnated paper insulation. Hence, vegetable insulating oil and transformer insulation paper has good compatibility in thermal aging tests.③The compatibility tests between vegetable insulating oil with polyester film,glass fiber and surface coating were simulated designed. The acid value, moisturecontent and breakdown voltage of vegetable insulating oil influenced by solid materialswere obtained. The mechanical strength of solid material and surface appearances ofmetal materials were analyzed. The types of insulating oil have no obvious influence onthe mechanical properties of polyester film and glass fiber. The surface appearances ofmetal material were still remaining intact. Therefore, vegetable insulating oil andtransformer solid material has good compatibility in thermal aging tests.