IS 335 defines the quality requirements for mineral insulating oil used in transformers and switchgear in India. The specification covers key properties such as dielectric breakdown voltage, moisture content, acidity, flash point, viscosity, density, oxidation stability, and inhibitor content. It distinguishes between uninhibited and inhibited oils and specifies acceptable limits and test methods. IS 335 is widely referenced in utility tenders, oil procurement contracts, and laboratory reports to ensure consistent oil quality, safety, and performance across manufacturers and suppliers.
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