A new diagnosis of the XLPE insulation with water treeing by space charge measurements with the thermal step method and water nuclear magnetic resonance imaging

In this paper the XLPE insulation degraded by water trees by water inception through external cracks in the PVC sheath has been studied by different techniques. Classical techniques has been used as the optical microscope examination of water trees after coloration, FT-IR mapping of cut thin films but also with other methods of investigation as space charges measurement by the thermal step method and magnetic resonance imaging (MRI) for water penetration. Three regions with water absorbance have been detected. The TSM technique is also a nondestructive tool to diagnose the presence of water treeing in cables insulation. The interpretation of the TSM results is in accordance with the observed morphology identified by optical microscopy and MRI.