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Time：2025-10-30 16:13:57 Reading volume：
Transformer oil contamination is a common issue that can reduce insulation strength, cooling performance, and overall transformer safety. Understanding the cause and type of impurities is essential for choosing the right purification method.
Start with oil sampling and testing to determine what contaminants are present.
| Type of Contamination | Typical Causes | Effects on Transformer |
|---|---|---|
| Solid particles (metal dust, fibers, carbon, etc.) | Aging of internal insulation, poor sealing, or maintenance debris | Clogs cooling channels, accelerates insulation wear |
| Moisture (water) | Air leakage, humid environment, poor oil storage | Reduces breakdown voltage, leading to partial discharge |
| Oxidation products (sludge, acids) | Long-term overheating or oxidation | Increases oil viscosity, decreases heat dissipation |
| Gases (air, hydrogen, etc.) | Leakage, aging, or internal faults | Reduces dielectric strength, increases risk of discharge |
(1) Filtration — Remove Solid Impurities
Use a precision oil filter or plate and frame filter to trap particles.
Filtration accuracy: ≤5 μm for high-voltage transformers.
Maintenance: Clean or ｒｅｐｌａｃｅ filter elements regularly.
Tip: Light contamination can be handled by on-site filtration alone.
(2) Vacuum Oil Purification — Deep Cleaning
The most efficient and comprehensive method for removing water, gas, and fine solids.
Operating principle: Under high vacuum and 50–60°C heating, water and gases evaporate and are extracted.
Recommended equipment: High-vacuum double-stage oil purifier (e.g., VFD series) — ideal for transformer maintenance and regeneration.
Advantages: High dehydration rate, strong degassing performance, and safe for continuous operation.
(3) Centrifugal Separation — Pre-Treatment
For oil with heavy sludge or water content, use a centrifugal separator first.
Separates contaminants by density through high-speed rotation.
Often used as a pre-treatment step before vacuum purification to enhance efficiency.
(4) Regeneration and Chemical Treatment
For aged or oxidized transformer oil, use a regeneration system with adsorbent clay or molecular sieves.
Removes acids, sludge, and discoloration.
Restores oil dielectric performance to nearly new levels.
Note: Should only be performed with professional equipment and supervision.
To keep transformer oil clean and extend service life:
Ensure sealed storage: Keep tanks and breathers tightly closed.
Filter before filling: Always filter new oil before injection.
Avoid humid conditions: Do not open systems in rainy or damp environments.
Regular oil testing: Check dielectric strength, moisture, and cleanliness annually.
Summary
If impurities are found in transformer oil:
Analyze the type of contamination (solid, water, oxidation, or gas).
Choose the proper purification method — filtration, vacuum treatment, or regeneration.
Prevent recontamination with correct sealing and regular testing.
For best results, use a high-vacuum transformer oil purifier to achieve deep dehydration, degassing, and fine filtration, effectively restoring oil dielectric strength and protecting transformer reliability.
