Study of space charge dynamics directly on power cables using the thermal step method

In recent years, many studies concerned with space charge have been performed on slabs and films made of materials for power cables. The structure of a cable and the distributions of the electrical and thermal stresses in the cable are different from a plaque-type sample. The thermal step method for space charge measurements (TSM) is directly applicable both to plaque-type samples and to insulating components of various geometries, with thicknesses up to 20 mm (cables, electrical machines windings, circuit boards, capacitor films). This work presents applications of the TSM to power cables. By using two different techniques of applying the thermal step (outer cooling and inner heating), we study the appearance and the evolution of the space charge within cable insulation as well as the effect of the manufacturing process on the radial and angular symmetry of a high voltage cable.