To understand the temperature-rise characteristic of vegetable oil insulated transformer in practical operation

the heat conduction and heat dissipation mechanisms of the transformer are analyzed by finite element method based on thermodynamics and fluid mechanics. A two-dimensional simplified model of the transformer is established. The finite element method is used to solve the temperature field of the model under load change

and the temperature field distribution of the vegetable oil insulated transformer under stable load is obtained. It is found that

compared with the mineral oil insulated transformer

the vegetable oil insulated transformer achieves better temperature-rise characteristic when the load factor K is not less than 1.5

but it has worsete mperature-rise characteristic when K is less than 1.5. Moreover

the temperature field distribution of the vegetable oil insulated transformer is calculated based on the given dynamic load curve

and the result shows that the temperature-rise characteristic of the vegetable oil insulated transformer is better than that of the mineral oil insulated transformer under higher load

while under lower load

the result is opposite.