Study Of Heat Exchange Of Oil Immerse Transformer

The oil immerse transformer is good at spreading heat, and it also has the characteristics of low exhausting, great capacity, low price and so on. At present almost all of the electric power transformers which are operating in the grid are oil immerse ones, above eighty percent of the oil immerse transformers are cooled by natural oil circulation. Currently the structure of setting plank to lead the oil in the coil is widely used in the oil immerse transformer in the domestic.Along with the arrival of the information-based society, the degree of the social dependence on the electric power is greatly raised; the request to the quality of the equipments supplying the power is also stricter than the past. More and more large transformers which used the auxiliary machines (pump fan) to spread heat forcedly in the past adopt the way of ONAN to spread heat. Now the engineering method to calculate the elevated temperature of the oil immerse transformer widely used in the factory can not coincidence with the actual one greatly. Sometimes it deviates very greatly, and can not be used to calculate the elevated temperature of high ignition temperature oil immerse transformer. How to improve the structure of the oil immerse transformer is an urgent problem faces to the domestic and international transformer industry.The method to calculate the average elevated temperature of oil, the elevated temperature of oil in the top structure, the winding elevated temperature, the core elevated temperature and the most hot point elevated temperature is given in this paper based on the application of engineering practices, the principle of heat transmission, the classic experimental standard of heat exchange and the study of the principle of heat-cool, the factors such as height above sea level,sola radiation, the structure of leading winding, noleading structure and the center height of heat sink which affect the elevated temperature of the oil transformer is also analyzed in the paper. The method is applicable to the calculation of the elevated temperature of the natural oil circulation transformer cooled by natural breeze and cooled by the fan, and it is also fit to the transformer which contains the cool off fluid as its oil or high ignition temperature oil. Through experience, the result of calculation is coincidence with the experimental data. The problem that the temperature calculated with the engineering method in the past cann't be consistent with the actul value is solved; within the national standard of transformer the cost of the material is reduced and the utilization ratio of material is improved.