PD performance of dielectric insulations in presence of low frequency conducted disturbances: a life model approach

The problem of how 50 Hz power supply voltage distortions affect PD activity and the lifetime of epoxy resin insulation systems, is addressed. In this aim, harmonics up to the 5^th were summed up to the voltage fundamental component changing the waveform from the sinusoidal into its peaked or flattened resulting shape. In a previous paper, life tests were performed using a sphere-plane electrode configuration; now the experimental research has been carried out, and an analysis of the PD aging phenomena was performed in both sinusoidal and non-sinusoidal life tests by a digital PD system. A good agreement has been:found between the physical phenomena involved during the aging and the obtained new related lifetimes. Finally, a life model is proposed to establish a functional relationship between the shape characteristics of the applied voltage and the failure times, thus providing a useful tool to evaluate the epoxy life changes due to the presence of voltage harmonics with respect to the sinusoidal supply