What maintenance activities are required for oil type transformers?

Typical maintenance includes periodic visual inspection for leaks, bushing condition checks, radiator and fan inspection, oil level and temperature verification, and checking breathers and silica gel for moisture saturation. Condition based oil testing includes BDV, moisture, acidity, tan delta, interfacial tension, and DGA, with furan tests for paper aging when needed. Tap changers are inspected and serviced per schedule. Cooling systems, pumps, and controls are tested. If results deteriorate, oil dehydration, filtration, or regeneration is performed, and any leaks or gasket issues are repaired to prevent moisture ingress.