Heat transfer coefficient α of insulation liquid used in power transformers, based on measurements

Poznan University of Technology, The Faculty of Electrical Engineering, 3A Piotrowo Str., 60-965 Poznan, Poland

^* Corresponding author: zbigniew.nadolny@put.poznan.pl

Abstract

Proper work of the power transformer is determined by many factors. One of them is relatively low operating temperature of the transformer. Too high temperature has many negative consequences, such as fast aging process of the insulation system. The temperature depends on the load of transmission line, losses and heat exchange in transformer. Heat exchange depends on heat transfer factor α of insulation liquid, which is a component of insulation system of transformer. This factor depends on many factors: the type of insulation liquid, the length of the heating element (windings), temperature, winding surface heat load, the winding position (vertical, horizontal), place on the winding (upper, middle or bottom part). The article presents the results of the measurement of heat transfer factor α as a function of type of insulation liquid, winding surface heat load, and place on the windings. The results will be used by designers and operators of power transformers.