Study on the morphology of XLPE power cable by means of atomic force microscopy

The long-term dielectric performance of underground power cable XLPE (cross-linked polyethylene) insulation suffers from poorly understood aging phenomena. A study of the morphological modifications of XLPE due to electrical aging may provide insight for a better understanding of aging mechanisms. The AFM (atomic force microscopy) technique has been used to study XLPE morphology of unaged, laboratory-aged and field-aged samples, whereby the soft XLPE surfaces were scanned with an oscillating AFM probe, to decrease the probability of surface modification. Images recorded on plasma-etched surfaces show many more structural details than an unetched surfaces. A XLPE cryo-microtomed surface from an unaged cable has been exposed to a low-energy electron beam, following which the exposed surface showed striking similarities with that of a field-aged cable.