How to maintain oil immersed transformer to extend service life?

Scientific regular maintenance can effectively slow down insulation aging, metal corrosion and oil deterioration, greatly prolong the overall service life of oil immersed transformers, especially critical for units running in coastal salt fog corrosive environment. Maintenance work is divided into daily routine inspection, periodic preventive maintenance, insulating oil management and targeted anti-corrosion maintenance.

1. Daily on-site routine inspection

Check transformer operating status at least once per day:

Observe oil level through oil level gauge to keep liquid within standard scale; replenish qualified insulating oil promptly when oil shortage caused by slight leakage.

Monitor surface temperature of tank and ambient temperature, listen for abnormal internal buzzing or bumping noise.

Inspect external corrugated tank/radiator, flange joints, bushings for oil seepage, rust and dirt accumulation; clean dust and salt deposits on outer surface regularly for coastal equipment.

Check breather desiccant: replace saturated pink moisture-absorbing silica gel to prevent humid & salty air entering the tank.

2. Regular periodic preventive maintenance

Quarterly maintenance

Clean dirt, salt crystallization and bird droppings on bushing and heat dissipation components; fasten loose connecting bolts of flanges and accessories evenly to avoid uneven gasket compression.

Annual overhaul

Carry out insulation resistance test with megohmmeter to track insulation condition of windings and casing.

Sample transformer oil for laboratory detection including breakdown voltage, moisture content and acid value.

Inspect grounding connection, ensure grounding resistance complies with specification; repair rusted grounding steel timely.

Major maintenance every 3–5 years

Drain old oil, clean internal tank sludge; check winding, tap-changer and core clamping insulation status; replace severely aged sealing gaskets.

3. Strict insulating oil maintenance

Insulating oil protects internal insulation and realizes heat dissipation, being the core of transformer lifespan:

Avoid long-time overloading operation to reduce oil thermal aging and acidification.

Prevent moisture and salt vapor infiltration via defective sealing and damaged breather.

Purify or regenerate oil via filtering machine when oil exceeds standard index; replace full oil if severe deterioration occurs.

4. Special anti-corrosion maintenance for coastal salt-fog area

Refinish scratched or peeling anti-salt-fog coating on tank and corrugated plates with heavy-duty anticorrosive epoxy paint every 1–2 years.

Increase cleaning frequency of heat dissipation gaps to remove accumulated salt dirt blocking heat exchange.

Upgrade ageing-resistant sealing rubber for all flange positions to slow salt-induced gasket failure and oil leakage.

5. Operational load control

Avoid frequent overload, three-phase unbalanced load and sudden large impulse load; match actual load with transformer rated capacity reasonably to cut excessive heat generation and insulation overheat damage.

References

APA 

Gibson, T. R., & Barnes, C. W. (2023). Preventive maintenance strategy to prolong service life of distribution oil-immersed transformers. IEEE Electrical Insulation Magazine, 39(5), 58–65. 

MLA 

Gibson, Thomas R., and Clara W. Barnes. "Preventive Maintenance Strategy to Prolong Service Life of Distribution Oil-Immersed Transformers." IEEE Electrical Insulation Magazine, vol. 39, no. 5, 2023, pp. 58–65,

GB/T 7714-2015

GIBSON T R, BARNES C W. Preventive maintenance strategy to prolong service life of distribution oil-immersed transformers[J]. IEEE Electrical Insulation Magazine,2023,39(5):58-65.