How dry-type transformers are cooled？

According to the convection heat dissipation theory, when the air near the coil surface is in a laminar flow state, the local heat dissipation efficiency on the coil surface is inversely proportional to the thickness of the thermal boundary layer on the coil surface. Therefore, the local heat dissipation efficiency of the coil surface is inversely proportional to the main flow velocity of the air flowing on the coil surface, so the local heat dissipation efficiency of the coil surface and the coil surface increase with the increase of the main air velocity. When the air on the coiling surface is in a mixed flow state, the local heat dissipation efficiency of the coiling surface is higher than that in the laminar flow state, which is basically independent of the main air velocity passing through the coiling surface.

Through a large number of numerical simulations, the position of the damper is summarized as the following cooling structure according to the special structure of the transformer. The damper is located on the upper part of the coil. The baffle is located above the larger horizontal airway. An insulating cylinder and a buffer are added to the low-voltage coil.

Therefore, the flow velocity at the coil surface must be as large as possible. The airflow on the surface of the coil should be as turbulent as possible. The cooling effect of the coil is better, and the operating capacity outside the nameplate of the dry-type transformer is larger. However, in practical applications, the system where the dry-type transformer is located has restrictions on the operating capacity other than the nameplate capacity, and the high wind speed is of little significance. The increase of the wind speed according to the fan noise increases rapidly, which cannot meet the users requirements for the noise limit value. .