Thermal modeling of disc-type winding for ventilated dry-type transformers

A thermal model for disc-type winding of ventilated dry-type power transformers is presented. The proposed model was based on fundamental heat transfer mechanisms, i.e. heat conduction, convection and radiation. All cooling surfaces were identified, and heat transfer coefficients for each identified surface were presented. The thermal model was applied to a ventilated dry-type power transformer rated at 2000 kV A under different load conditions. Temperature distributions were calculated, and the hottest-spots were located accordingly. The temperatures for the predicted hottest-spots were measured by an infrared thermometer, and they were compared with the temperatures calculated by the model. They are in good agreement.