Dependence of return voltage characteristics on change of insulation conductivity and polarization resistance

A demand for a reliable diagnostic method is growing by the increase of the age of equipment. The return voltage characteristics such as the maximum of return voltage, the initial slope of return voltage and the time to peak value dependencies on charging time are discussed in this paper. The analysis of these characteristics increases the information of the insulation properties of equipment. The increase of conductivity and decrease of polarization resistance are closely related with the ageing processes of insulation. The changes of these dielectric phenomena can be seen by the analysis of return voltage characteristics. The theoretical study of the polarization index particularly used for the assessment of insulation systems is given in paper.