Low frequency dielectric response of thermally degraded epoxy-mica insulation

Dielectric spectroscopy measurement is essentially a dissipation factor measurement performed at multiple frequencies ranging from few mHz to kHz. Low frequency dielectric spectroscopy measurement has been performed on number of sound and thermally aged epoxy-mica representative laminates and on actual motor coils. Dielectric loss angle, power factor, capacitance was measured at frequencies ranging from 1 mHz to 1 kHz. The dielectric response exhibited by of thermally aged epoxy-mica insulation at lower frequencies shows the predominant influence of interfacial polarization on the total dielectric response of epoxy-mica layer.