Comparison of different dielectric characterization methods with TSC spectra of silicone rubber filled with carbon black nanofillers

High voltage direct current (HVDC) power transmission is becoming increasingly competitive to high voltage alternating current (HVAC) power transmission, especially for bulk power transmission over long distances. For crossing wide metropolitan areas, long distances in the open sea, or latterly in Germany the planned underground North-South DC links, especially extruded HVDC cable lines are attractive because of significant advantages over other insulation types. Nevertheless, in HVDC insulation systems the electric field distribution is much more complex than in AC systems, because it strongly depends on the conductivities of the insulation. Especially the presence of space charges can lead to an increased electric field strength up to the failure of the device. Due to the mentioned challenges it is significant to develop new insulating materials suitable for HVDC applications. One promising approach is to introduce nanofillers in the insulating matrix for space charge suppression. The purpose of this paper is to present the results of the influence of nanoscale carbon black (CB) in liquid silicone rubber (LSR). Besides volume resistivity, dielectric breakdown strength is determined to check the influence of the CB concentration. In addition, TSC (Thermally Stimulated Current) measurements are performed on LSR samples with different CB concentrations to evaluate their properties.