Frequency measurement of the dielectric properties of semiconductive layers in XLPE-cables

Measurements of the semiconductive layers over broad frequency (300 kHz-500 MHz) and temperature ranges (20-90°C), constant pressure as well as a well-defined humidity are presented in this work. The measured results are given as complex permittivity and partly as conductivity, which represents the imaginary part of the complex permittivity. Extracted cable samples and produced hardboards, made from the same material, are used as samples. The extracted samples are classified in inner and outer layers of the semiconductive screens and of a 380 kV energy cable. The pressed hardboard sample is made from the same compound (LE 0500, Borealis) as the 380 kV power cable. The aim of the work is to investigate the inner and outer semiconductive layer of a power cable as well as the pressed semiconductive layers. The work is separated in basics regarding the semiconductive layers, a short presentation of the measurement device, the sample manufacturing and the results of the investigation.