Oxidation stability assessment of a vegetable transformer oil under thermal aging

Yang Xu, Sen Qian, Q Liu, Z D Wang

    Research output: Contribution to journalArticlepeer-review


    Vegetable oil is one of the alternatives to replace mineral oils in transformers. This paper focuses on oxidation stability assessment of a vegetable transformer oil under accelerated thermal aging at 110\&\#x00B0;C with various durations up to 2500 hours. Oil samples were aged under open condition to stimulate the oxidation process, as well as under sealed condition to provide a comparison. A number of parameters including acidity, {DC} conductivity, dielectric dissipation factor ({DDF}) and viscosity were measured to see their responses to oxidation process of the vegetable oil. The results showed that viscosity responds towards oxidation more than hydrolysis whereas acidity responds strongly to both oxidation and hydrolysis, since besides oxidation, hydrolysis of the vegetable oil also generates acid byproducts. Of more importance, oxidation stability, in the term of oxidation induction time ({OIT}), of thermally aged vegetable oils was investigated by using Pressure Differential Scanning Calorimetry ({PDSC}) method. As there was no standard on {PDSC} method available for vegetable oils, various measuring temperatures were tried and 130\&\#x00B0;C was found to be suitable for the investigated vegetable oil. The results showed that {OIT} of open samples decreases obviously with aging time until reaching the bottom plateau at 1000 hours, while {OIT} of sealed samples stays at a high level until the end of aging at 2500 hours. Therefore, {OIT} measured by using {PDSC} is appropriate to reflect oxidation stability of the vegetable oil. This was further confirmed by the corresponding consumption of antioxidant and generation of peroxides, dissolved decay products.
    Original languageEnglish
    Article number6783062
    Pages (from-to)683-692
    Number of pages10
    JournalDielectrics and Electrical Insulation, IEEE Transactions on
    Issue number2
    Publication statusPublished - 10 Apr 2014


    • acid byproducts
    • acidity
    • Aging
    • antioxidant consumption
    • {DC} conductivity
    • DDF
    • dielectric dissipation factor
    • differential scanning calorimetry
    • dissolved decay products
    • electrical conductivity
    • hydrolysis
    • insulation testing and aging
    • Oil insulation
    • OIT
    • oxidation
    • oxidation induction time
    • oxidation stability
    • oxidation stability assessment
    • {PDSC} method
    • peroxides generation
    • pressure differential scanning calorimetry
    • stability
    • temperature 110 degC
    • Temperature measurement
    • thermal aging
    • thermally aged vegetable oils
    • Thermal stability
    • time 1000 hour
    • time 2500 hour
    • transformer oil
    • vegetable oils
    • vegetable transformer oil
    • viscosity


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