Condition Monitoring of Epoxy Mica Composite Insulation Used in Rotating Machines Employing Electric Modulus

In this contribution, a novel technique for condition monitoring of epoxy mica composite insulation is proposed employing complex electric modulus. The complex electric modulus is a powerful technique to examine the dielectric properties of insulating materials, as it is directly determined by the polarization and subsequent relaxation behavior of the dipoles. Considering the aforesaid fact, in this study electric modulus is used to study the aging behavior of epoxy mica composite insulation, which is used as a popular insulating material in rotating machines. For this purpose, experiments were conducted on stator bar epoxy mica composite insulation after performing accelerated thermal aging for 200 hours, 400 hours and 600 hours, respectively. For each sample, the real and imaginary part of complex dielectric modulus was computed from 0.1mHz-1kHz to observe their frequency dependent relaxation behaviors. From the nature of variation of real and imaginary parts of complex modulus, two aging sensitive characteristic parameters were extracted. Further analysis revealed that the extracted parameters can be utilized to estimate the aging condition of the epoxy mica composite insulation. The proposed method can be implemented for real time condition monitoring of rotating machine insulation.