Analysis of the structure of the extruded insulation of high-voltage cables by a video microscopy method

The results of an investigation of the morphology of the polymer insulation of power cables, carried out using computer-aided video-enhanced microscopy are presented. To study the morphology the following methods were used: a dark-field method, a phase and differential interference contrast method, an anoptral and polarization microscopy method and an asymmetric illumination contrast method. It is established that the insulation structure is heterogeneous and anisotropic. This leads to non-uniformity and anisotropy of the local electric strength (electric treeing resistance). The establishment of a relationship between the electric strength and the morphology enables ways of improving the technology to ensure an increase in cable reliability to be developed.