Time domain measurements of dielectric response in oil-paper insulation systems

The results of dielectric response measurements in the time and frequency domain on homogeneous impregnated pressboard and on series arrangements of pressboard sheets and oil ducts are presented. A simple equivalent circuit is proposed to model oil-paper insulation systems for single impregnated pressboard sheets as well as for multi-layer arrangements. This equivalent circuit which is derived from relaxation current measurements is then used to calculate recovery voltages as well as the frequency-dependent permittivity. Finally it is shown that the same procedure can be applied to quantify the dielectric response properties on high voltage power transformers.