Effect of Composition and Morphology on the Dielectric Response of Cellulose-based Electrical Insulation
2015 (English)In: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 22, no 4, 2339-2348 p.Article in journal (Refereed) Published
Different wood-fibre based papers were characterized by dielectric spectroscopy, mechanical testing and microscopy. The data obtained were utilized to investigate the relationship between the chemistry, morphology and density of a paper and its permittivity and dielectric loss. The density strongly influences the dielectric response, but the response is not affected by the way the density has been achieved; by pressing the paper during drying or by mechanical treatment of the fibres before sheet preparation. The chemical composition of the pulp influences the polarization, dielectric loss and charge transport. It was found that paper-vacuum and paper-oil combinations can be represented by series-equivalent circuits. The permittivity of paper made from electrical grade kraft pulp, used in e.g. high voltage transformers, without any porosity is estimated to be 5.3 and tan delta to 0.01-0.02 at 50 Hz and 70 degrees C. The lignin and hemicellulose content of the kraft pulp do not affect the real part of the permittivity significantly, but the dielectric losses increase with increasing lignin and hemicellulose content in both oil and vacuum at 50 Hz and 70 degrees C.
Place, publisher, year, edition, pages
2015. Vol. 22, no 4, 2339-2348 p.
Paper insulation, interconnected systems, dielectric materials, permittivity, dielectric losses, dielectric measurements, dielectric polarization, cellulose, hemicellulose, lignin
IdentifiersURN: urn:nbn:se:kth:diva-173279DOI: 10.1109/TDEI.2015.005017ISI: 000359591600072ScopusID: 2-s2.0-84939557888OAI: oai:DiVA.org:kth-173279DiVA: diva2:852638
QC 201509092015-09-092015-09-092015-09-09Bibliographically approved