On the impacts of ageing and moisture on dielectric response of oil impregnated paper insulation systems

In this contribution, dielectric measurements in the frequency domain spectroscopy (FDS) were undertaken on oil impregnated paper samples in order to assess, with accuracy, the state of the solid insulation used in power transformers. The dielectric dissipation factor (tanδ) and the angle (phase shift) of the impedance of new and aged oil impregnated paper samples were measured; the moisture content served as parameter. These investigations aim at improving our understanding onto the effects of aging and moisture on the quality of the solid insulation (paper and paperboard) used in power transformers. Such investigations might be helpful in the separation of these two effects when doing FDS measurements.