| Large power transformer is one of the core equipment in power system,and oil paper insulation is its main insulation.Moisture has degradation effect on the insulation status of oil paper and reduces its dielectric properties.The traditional drying method of transformer not only takes time and consumes power,but also has some shortcomings such as the failure of maintenance.Zeolite A has good water adsorption performance,which provides a new idea for on-line drying method of transformer.However,the water adsorption characteristics of zeolite A in oil paper insulation are not clear,and the material can not be directly applied to the on-line water removal device.In order to fill the lack of research in this field,it is necessary to carry out the research on the water adsorption characteristics of zeolite A in insulating oil and the interaction between zeolite A and insulating oil.In this paper,the transformer insulating oil was humidified at 60℃ and 90℃respectively.The zeolite 3A and zeolite 4A from three manufacturers were selected as water removal materials.The saturated water adsorption capacity of zeolite under different conditions was measured.The results show that the water adsorption capacity of zeolite 4A is larger than that of zeolite 3 A at two temperatures.At 60℃,the maximum saturated water adsorption of zeolite 4A is 20.68%.At 90℃,the maximum saturated water adsorption of zeolite 4A is.10.68%.The transformer oil was humidified to different degrees under five temperature conditions.Three different manufacturers of zeolite 3A and zeolite 4A were selected as the water removal materials.The water content of the oil was tested every 12 hours.The water content curve of the oil with time was obtained within 4 days.The water adsorption of zeolite 3A and zeolite 4A on the transformer oil under different conditions was analyzed.At 20℃,the water adsorption rate of zeolite 3A is similar to that of zeolite 4A;At 40℃,60℃,80℃ and 90℃,the water adsorption rate of zeolite 4A is higher than that of zeolite 3A.The insulating oil was treated by accelerated thermal status,and the effects of zeolite on dielectric properties and water adsorption of insulating oil were tested.The results show that the zeolite has no effect on the dielectric properties of insulating oil,and the status of insulating oil will affect the water adsorption of zeolite.When the insulating oil is aged for 10 years,under the condition of 5%breakdown probability,the breakdown voltage of the insulating oil dried by the 4A zeolite from the manufacturer 1 is 6.47%higher than that of the non-drying insulating oil.When the insulating oil is aged for 20 years,under the condition of 5%breakdown probability,the breakdown voltage of the insulating oil dried by the 4A zeolite from the manufacturer 1 is 39.167%higher than that of the non-drying insulating oil.When the insulating oil is aged for 30 years,under the condition of 5%breakdown probability,the breakdown voltage of the insulating oil dried by 4 A zeolite from the manufacturer 1 is equivalent to that of the insulating oil not dried. |
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