Heat circuit modeling for calculating temperature rise of ungrounded-wye delta traction transformer

The calculating results are not accurate enough when the inner temperature rise of traction transformer is estimated by IEC method, since it doesn't consider the factors such as impacted loads. On basis of studying the characters of the traction loads, production and transfer of the heat inside the traction transformer are analyzed. Then referring to the basic electrical principle, heat circuits for analyzing inner temperature rise of ungrounded-wye delta traction transformer are erected, according to which, the temperature rise calculating model is obtained. This heat circuit model is validated by experimental (fiber-optic test) results on experimental ungrounded-wye delta traction transformer working under simulated impacted loads. The results are also compared with IEC method, and it shows that heat circuit model is more valid to calculate the inner temperature of ungrounded-wye delta traction transformer than IEC method.