The analysis of the convection heat transfer and the calculation of coal dry-type transformers’ temperature filed are greatly affected by the convection heat transfer coefficient

which is difficult to be measured accurately. In order to get convection heat transfer coefficient more precisely

the mathematical model of fluid-solid coupling field of the dry-type transformer was proposed based on FEM. Then the three-dimensional temperature field and airflow field were simulated by using the finite element software Fluent. Consequently

the temperature distribution of transformer was derived. Finally

the influences of harmonic and load coefficient on loss and temperature rise were analyzed. The relationships between the harmonic loss and temperature rise and the order of harmonic

as well as load coefficient

were gained. In comparison with the analytical results

we have verified that the distribution of the temperature filed can be analyzed more precisely by fluid-solid coupling model considering the existence of air flow. Meanwhile

the transformers’ harmonic loss and temperature rise will increase

and gradually tend to flatten out as the the order of harmonic increases

while they dramatically rise as the load coefficient increases. Therefore

the results can provide a practical reference for establishing effective monitoring on dry-type transformers

so as to reduce the loss

prolong the life

and guarantee safe and stable operation of transformer.