Return voltage measurements - the step from experimental data to a relevant diagnostic interpretation

The condition of service aged medium voltage cables can be assessed by measuring the dielectric response of the insulation. In time domain this can be done via return voltage or/and depolarization current measurements. The paper deals with the interpretation of experimental results of return voltage measurements and discusses the relevance of different measurement conditions and the meaningfulness of the different diagnostic parameters chosen. Special emphasis is taken on the p-factor, a parameter that seems to be appropriate for all types of insulating materials.