The condition of transformer insulating oil is one of the best indicators of overall transformer health. Over time, heat, oxygen, and moisture drive oxidation and chemical changes that degrade both oil and cellulose insulation.
Interfacial Tension (IFT) and Acid: IFT is the leading indicator of oil oxidation. As oil oxidizes, acids and polar compounds form, lowering the IFT and raising the acidity. The graph provides a visual representation of what’s happening inside the transformer as it ages over time.
Oxidation Inhibitors (DBPC/DBP): Added to slow oxidation. The recommended range is 0.15-0.30% by weight; below 0.09% the oil is considered non-inhibited. One depleted, aging accelerates rapidly.
Routine monitoring of moisture, acidity, IFT, and inhibitor levels helps formulate maintenance decisions to extend the service life, maintain insulation integrity, and prevent costly transformer failures.
Want to better understand how your transformer ages over time? Explore the transformer life cycle and discover how routine transformer oil diagnostics help identify aging, guide maintenance decisions, and maximize the reliability and service life of your critical assets.