Title:	Various aging processes in a paper-natural ester insulation system in the presence of copper and moisture
Authors:	Trnka, Pavel Hornak, Jaroslav Prosr, Pavel Michal, Ondřej Wang, Feipeng
Citation:	TRNKA, P., HORNAK, J., PROSR, P., MICHAL, O., WANG, F. Various aging processes in a paper-natural ester insulation system in the presence of copper and moisture. IEEE Access, 2020, roč. 8, č. 2020, s. 61989-61998. ISSN 2169-3536.
Issue Date:	2020
Publisher:	IEEE
Document type:	článek article
URI:	2-s2.0-85083428966 http://hdl.handle.net/11025/39583
ISSN:	2169-3536
Keywords in different language:	aging;dielectrics;hydrogenation;hydrolysis;oil insulation;paper-oil insulating system;natural ester;complex permittivity
Abstract in different language:	This article adds more information to the problem of natural ester use as an electroinsulating uid in cellulose paper-oil systems, e.g., for use in power transformers. An accelerated thermal aging (120, 140 and 160 C) of samples consisting of cellulose paper (transformerboard), a treated natural ester (ltered, basic Al2O3, 0.53% DBPC), a copper plate and moisture was studied. Research was especially focused on the impact of moisture on the aging of the above system. Samples with three different oil moisture levels (80, 143 and 305 ppm water content) were subjected to thermal aging to display the change in a selection of properties (tan, acid number, water content). For a study of the polarization effects, broadband dielectric spectroscopy (BDS) was performed to observe the complex permittivity and conductivity dependencies on the temperature and frequency (30 C, 0.01107 Hz). Havriliak-Negami (H-N) diagrams were used to further understand the results. The degradation products during thermal aging were recognized by Fourier transform infrared (FT-IR) spectroscopy. Hydrolysis and hydrogenation occurred in the insulating system with a natural ester aged by elevated temperatures, which is in contrast to CO2 formation in the case of electric aging. The results showed an increase in the acid number, dissipation factor, and number of hydrolysis and hydrogenation products. Furthermore, changes in polarization were observed as a consequence of the thermal aging of paper-natural ester insulation system with the presence of copper and moisture.
Rights:	© IEEE
Appears in Collections:	Články / Articles (RICE) Články / Articles (KET) OBD

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