The Influence of Polarity Reversal on Leakage Current in XLPE Samples

To ensure the effectiveness of insulation in MVAC cables and to facilitate multiphysics finite element method (FEM) simulations for DC applications, it is crucial to evaluate the electrical properties of insulation materials at DC. In this regard, a critical aspect of this assessment is DC conductivity, which is typically determined through leakage current (LC) measurements. In this contribution, plate samples taken from 12/20 kV and 19/33 kV XLPE MVAC cables are utilised to conduct LC measurements. By using line commutated converter (LCC) technologies polarity reversals (PR) are performed to control the load flow of the DC transmission or distribution system. Measuring LC during PR is essential for assessing the reliability of the cable insulation. This study, therefore, presents findings from LC measurements at constant electric and thermal stress, with PR cycles after every 6 hours. This provides valuable insights for the development and optimisation of MVDC cables.