In this paper an electrical equivalent of the enthalpy based on dissipation factor tests of compound Mica-Epoxy Resin used as insulating material in the stator bars of electrical machines is shown. To this, 15 samples were designed and subjected to Step Voltage Endurance Test (SVET) at a constant temperature of 90degC. Before and during each period of aging, the dielectric losses of each of the sample were measured at different voltages from 2 to 10 kV in a temperature range. The results of the dielectric loss were used to determine the caloric coefficients K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v</sub> and the glass transition temperature T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> of the material. The incidence of partial discharge based on the Tip-Up on these parameters in the various stages of aging of the insulation is analysed as well.