Correction of temperature for dielectric measurements in time domain

Summary

Dielectric measurements in time domain, so called PDC measurements (polarization and depolarization current) are used to determine the conductivity of insulation materials for both, the design of HVDC insulation systems as well as for ageing condition assessment of insulating systems. For evaluation of PDC measurement results it is quite important to compare the data with reference parameters or curves (so called fingerprints) or simulation results based on material sample data. As the conductivity of insulating materials is strongly influenced by temperature (and other parameters like field strength and ageing condition or water content), the temperature at which the measurement was performed has to be corrected to a reference temperature in order to assess the condition of the insulating system. Up to now it was only known, how to perform the temperature correction in frequency domain. This paper describes the process of temperature correction and gives a physical interpretation of the temperature dependence of dielectric measurements, so that it is possible to transfer the process of temperature correction to time domain. It is shown, how this temperature correction can be used in practice for ageing condition assessment. The investigations were done at oil-paper insulation systems, but as shown, the method of temperature correction can be used at other solid dielectrics like resin impregnated paper as well.

Additional informations

Keywords

Dielectric measurements, PDC, temperature correction, ageing condition assessment