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Energies 2015, 8(8), 7690-7702;

Measurement of the Relative Free Radical Content of Insulating Oils of Petroleum Origin

Canada Research Chair on Insulating Liquids and Mixed Dielectrics for Electrotechnology (ISOLIME), University of Quebec at Chicoutimi, 555 Boulevard de l'université, Chicoutimi, QC G7H 2B1, Canada
Insoil Canada Ltd., 231 Hampshire Place NW, Calgary, AB T3A 4Y7, Canada
Author to whom correspondence should be addressed.
Academic Editor: Paul L. Chen
Received: 31 May 2015 / Revised: 15 July 2015 / Accepted: 21 July 2015 / Published: 28 July 2015
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Oil/paper insulation degradation in transformers involves chemical and physical changes in the materials. Some of the chemical reactions involve very reactive intermediates called free radicals. Free radicals play a major role in a wide variety of ageing processes. The detection of these reactive species in oil may, in principle, provide useful information for monitoring oil degradation. This manuscript details a laboratory technique, which determines the relative content of free radicals in insulating oils of petroleum origin by a spectrophotometric method. Free radicals may be formed in oils under operating or test conditions. The procedure enables the determination of the relative concentration of free radicals, which can act as the precursors of decay products such as charge carriers, oxidized molecules, as well as polymerization products. The technique involves using a reactive free radical reagent, 2,2-diphenyl-1-picrylhydrazyl (DPPH), added to oil to assess free radical concentration. This method is applicable to new, reclaimed, or used oils as well as naturally or artificially oxidized oil (the cause of aging can be chemical, physical, or electrical). In this contribution, free radicals were assessed following electrical discharge application in oil. View Full-Text
Keywords: free radicals; insulating oil; reaction kinetics free radicals; insulating oil; reaction kinetics

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Fofana, I.; Sabau, J.; Betie, A. Measurement of the Relative Free Radical Content of Insulating Oils of Petroleum Origin. Energies 2015, 8, 7690-7702.

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