Conductivity of pressboard for HVDC insulation systems
Authors
Fabian Schober
University of Applied Sciences Würzburg-Schweinfurt, Institute for Power Engineering and High Voltage Technology Ignaz-Schoen-Strasse 11, 97422 Schweinfurt, Germany
Stephan Harrer
University of Applied Sciences Würzburg-Schweinfurt, Institute for Power Engineering and High Voltage Technology Ignaz-Schoen-Strasse 11, 97422 Schweinfurt, Germany
Andreas Küchler
University of Applied Sciences Würzburg-Schweinfurt, Institute for Power Engineering and High Voltage Technology Ignaz-Schoen-Strasse 11, 97422 Schweinfurt, Germany
Frank Berger
Technische Universität Ilmenau, Department of Electrical Apparatus and Switchgear Gustav-Kirchhoff-Strasse 1, 98693 Ilmenau, Germany
Marcus Liebschner
Aalen University, Optics and Mechatronics Beethovenstrasse 1, 73430 Aalen, Germany
Christoph Krause
Weidmann Electrical Technology AG, Technology Services and Innovation Neue Jonastrasse 60, 8640 Rapperswil, Switzerland
Wolfgang Exner
Weidmann Electrical Technology AG, Technology Services and Innovation Neue Jonastrasse 60, 8640 Rapperswil, Switzerland
The cellulosic material pressboard is a key component in insulation systems for HVDC (high-voltage direct current) equipment. Pressboard compounds are considered from a chemical point of view in order to link it in a subsequent study with electric conduction processes in pressboard. For a better understanding of pressboard, its manufacturing is described and fiber geometry is evaluated by SEM (scanning electron microscopy) analyses. Especially for HVDC insulation, pressboard conductivity is the most important property. For an air-impregnated pressboard sample, the dependence of conductivity on time, temperature and water content is presented. For this purpose, step response measurements in time domain are performed with a sensitive current device. Furthermore, the influence of oil-impregnation on pressboard conductivity is evaluated. The conductivity of oil-impregnated pressboard is up to 13 times higher than the conductivity of unimpregnated pressboard for the given conditions.