Measuring partial discharges in MV cables under DC voltage: procedures and results in steady state conditions

Starting from measurements performed on insulation models, estimation of partial discharge inception voltage, PDIV, and inference of the different behavior of PD for a MV cable models are presented and discussed. The estimations are validated through laboratory testing on a cable with an artificial defect. It is shown that PDIV under DC can become considerably higher or lower than that under AC, depending on temperature and material properties, which affect PD repetition rate as well. However, resorting to the model presented in this paper, measuring PD under AC will help to identify and validate the results of the PD DC measurements.