My thesis deals with the investigation of temperature dependence of dielectric properties of low voltage PVC cable insulation.
At first, I introduced the degradation processes of insulations, the factors of insulation ageing and the basics of lifetime calculation of accelerated thermal ageing tests.
After that I studied the non-destructive dielectric measurements. The dielectric degradation process can be investigated by the measurement of conductive and polarization processes. Previous investigations have shown that the thermal dependence of these processes are very different, and associated with several activation energies.
At last, I evaluated the measurement results. The dielectric properties were measured by the voltage response (VR) method and by the improvement of this method the dielectric spectrum can be investigated. The measurements were performed at five different temperatures, 30°C to 70°C, than the cables were aged at 110°C for 900 hours. After that I again performed the measurements. I plotted the results graphically and I drew conclusions.