Thermodynamic study of compound Mica — Epoxy Resin based on dissipation factor tests — Enthalpy

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 90°C. 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_v and the glass transition temperature T_g 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.