What temperature and oxidation limits apply to a mineral oil transformer in service?

Limits are typically managed through top oil and winding temperature targets set by transformer design and loading guides. Higher temperature accelerates oxidation of mineral oil and aging of paper insulation, increasing acidity and sludge formation. Operators control loading, cooling stage operation, and monitor oil quality. Oxidation limits are assessed by tracking acidity, interfacial tension, inhibitor depletion, and sludge indicators. If limits are approached, oil treatment or replacement is planned to restore performance and reduce risk.