Analysis of the total alternating current through insulating polymers under accelerated thermal aging

This work is devoted to analyze the alternating dielectric current flows through polymeric materials used in electrical cables insulation. The insulating compound based on poly (vinyl chloride) (PVC/B), used as electrical insulation in medium and low voltage cables manufactured by the electric cables factory CABEL of Algiers (Algeria), was chosen as the studied material. Accelerated thermal aging on circular shaped samples of PVC/B was performed at two temperatures, 80°C and 120°C, during 2016 hours (84 days). Spectral analysis of the obtained current waveform parameters, such as magnitude and harmonic content as indicated by the total harmonic distortion (THD), were analyzed using fast Fourier transform (FFT) method at different stages during aging time and for five levels of AC applied voltage, ranging from 3 kV to 15 kV. Through this work, the study of the current waveforms offers significant information about the degradation level of the material, which can be used for the diagnostic of electrical cables.