Thermal analysis of varnish treated insulating papers for transformers

This paper describes the thermal characteristics of varnish treated Kraft and aramid papers in order to understand the effect of the varnish concentration on the heat flow pattern. The insulating papers were impregnated by the varnish diluted with solvent and then dried completely. The heat flow of the specimens was obtained using a differential scanning calorimeter (DSC) and analyzed. As a result, the heat flow curves of varnish and varnish treated insulating paper linearly changed with the varnish concentration and it was confirmed that the varnish concentration could be determined by comparing with the changing patterns in heat flow of the varnish treated insulating papers with temperature.