Dielectric Frequency Measurement of Semiconductive Layers in Xlpe Cables

The work concerns measurements on two different semiconductive cable compounds. The measurements investigate the cable compounds over a broad frequency range (between 1 Hz and approximately 100 MHz) at a defined temperature (20°C), humidity and pressure. The measurement results give the complex permittivity and the resistance or conductance of the semiconductive samples. The samples are extracted from regular energy cables and characterized in preparation for measurement. Due to the sample preparation and extraction from the cable, the samples are slightly different in their geometries, and therefore the geometrical data for each measured sample are taken into account in the calculation, and hence in the measurement results. The investigated samples are extracted from a 380 kV, a 110 kV and a 15 kV energy cable. The samples are different in their semiconductive material compounds; a better compound is used in the 380 kV cable than in the other two. The compound was from Borealis for all sample types. The compound LE 0500 is used for the 380 kV cable and LE 0595 for the 110 kV and 15 kV cable samples. The investigation results are separated by voltage level and position in the cable. The position refers to either the inner or the outer semiconductive layer. The paper is separated into a brief overview of the measurement setup, basic details of the semiconductive layers/compounds, the extraction of the samples and the measurement results. The results show the difference in the compounds and the variation in the samples.