Key properties include dielectric strength, low moisture content, low acidity, high resistivity, stable dielectric dissipation factor, suitable viscosity for cooling, adequate flash and fire points, and good oxidation stability. Interfacial tension is important because it indicates contamination and aging byproducts that can lead to sludge. Density and specific heat affect cooling behavior. Corrosive sulfur behavior matters for copper and paper compatibility. These properties collectively determine whether the oil can reliably insulate and cool the active parts while supporting long term insulation life and diagnostic monitoring.
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