Dielectric reliability depends on oil dryness, cleanliness, resistivity, and dissipation factor. High moisture reduces breakdown voltage and increases partial discharge risk. Acids and sludge reduce resistivity and raise losses, accelerating insulation aging. Particles can create local electric field intensification and lead to discharge. Good oil condition maintains stable insulation margins across bushings, windings, and paper barriers. Regular testing and oil treatment help preserve dielectric reliability and reduce the risk of internal faults and flashover events.
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