Correlation between return voltage and relaxation current measurements on XLPE medium voltage cables

The destruction free determination of the ageing status of a polymeric cable insulation is a significant issue for the assessment of remaining life time. The ageing status can be determined by measuring the dielectric properties in time or frequency domain. Because of the nonlinear behaviour of aged polymeric materials, time resolved measurements seem to be more meaningful. In time domain the dielectric properties can be obtained by measuring the relaxation current or the return voltage. Due to the different results and interpretations of those measurements, this paper discusses the comparability of these procedures. Furthermore, influences of electromagnetic disturbances are discussed.