Investigation of dielectric properties of cable insulation by the extended voltage response method

The voltage response method is based on the measurement of the decay and return voltages on a charged and shorted dielectric. From the initial slopes of these voltages, two material properties, namely the specific conductivity and the polarization conductivity can be determined. By changing the shorting time of the charged insulation the polarization processes can be examined separately and the whole polarization spectrum can be investigated more precisely. This paper introduces how the voltage response measurement technique is extended by the variation of discharging times. Measurements on oil-paper and polymeric insulated cables were carried out and the results have been compared. By this measurement method the differences of polarization processes of different insulating materials can be investigated more precisely.