Understanding the ageing aspects of natural ester based insulation liquid in power transformer

Bandara, Kapila, Ekanayake, Chandima, Saha, Tapan Kumar and Annamalai, Pratheep Kumar (2016) Understanding the ageing aspects of natural ester based insulation liquid in power transformer. IEEE Transactions On Dielectrics and Electrical Insulation, 23 1: 246-257. doi:10.1109/TDEI.2015.004744

Author Bandara, Kapila
Ekanayake, Chandima
Saha, Tapan Kumar
Annamalai, Pratheep Kumar
Title Understanding the ageing aspects of natural ester based insulation liquid in power transformer
Journal name IEEE Transactions On Dielectrics and Electrical Insulation   Check publisher's open access policy
ISSN 1070-9878
Publication date 2016-02-01
Sub-type Article (original research)
DOI 10.1109/TDEI.2015.004744
Open Access Status Not Open Access
Volume 23
Issue 1
Start page 246
End page 257
Total pages 12
Place of publication Piscataway, NJ, United States
Publisher Institute of Electrical and Electronics Engineers
Language eng
Formatted abstract
Cellulose based insulation materials and mineral oils have widely been used in liquid filled transformers. Environmental and fire-safety concerns have accelerated the use of Natural Esters (NE) as a sustainable alternative to mineral oil. There is a rapid growth of their application for distribution level transformers. To ensure a safe and long-term operation of the vegetable oil filled transformers, it is necessary to clarify the knowledge gaps with respect to the ageing of vegetable oil impregnated cellulose and insulation diagnostic methods. The condition monitoring of mineral oil filled transformers has been well characterised, due to the numerous laboratory and field studies conducted during the past several decades. The application of these available condition monitoring techniques for NE filled transformers is yet to be validated as the use of NE for power transformers is in the evaluation stage. In this paper the performance of NE as insulation in transformers by evaluating the ageing of NE impregnated cellulose pressboard is presented. For this purpose, an accelerated ageing experiment has been carried out in sealed tubes at 120 °C. The ageing of oil impregnated pressboard has been characterised by decrease in the degree of polymerisation (DP) of pressboard, and the formation of both 2-furfuraldehyde and dissolved carbon dioxide (CO2) in the oil. The structural changes of cellulose have been supported by Fourier Transform Infrared (FTIR) spectra. Moreover, the results have been compared with cellulose insulation samples aged under similar conditions in conventional mineral oil. Acidity value, dissipation factor and viscosity measurements have been used to compare the stability of NE in a transformer operating environment to mineral oil.
Keyword Cellulose
Degree of polymerisation (DP)
Dissipation factor dissolved gas analysis (DGA)
Fourier transform infrared spectroscopy (FTIRS)
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

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