In power systems, the oil-immersed transformer is widely used due to its stable insulation and excellent heat dissipation performance. However, over time, the transformer oil inside the oil-immersed transformer gradually ages, affecting the insulation performance and safe operation of the equipment. To extend service life and maintain operational efficiency, it is crucial to prevent transformer oil aging effectively.
This article explains the main causes of transformer oil aging and provides scientific prevention measures for reference and implementation.
1. Main Causes of Transformer Oil Aging
Thermal Oxidation: During operation, oil-immersed transformers generate high temperatures that trigger oxidation reactions between the oil and oxygen in the air. These reactions produce aging byproducts such as acids, aldehydes, and ketones, which reduce insulation performance and corrode metal parts.
Moisture and Contaminants: Moisture and dust from the external environment can enter the transformer, increasing the oil’s water content, reducing breakdown voltage, and accelerating insulation degradation through corona and partial discharges.
Electrical Stress: Long-term exposure to high electric fields can alter oil molecular structures, producing conductive carbon particles that form “carbon bridges,” posing serious safety hazards.
Metal Catalysis: Metal particles such as copper and iron inside the oil-immersed transformer act as catalysts at high temperatures, accelerating oil decomposition and aging.
2. Effective Measures to Prevent Oil Aging
Select High-Quality Transformer Oil: Premium mineral or synthetic oils offer better oxidation resistance, lower moisture content, and higher breakdown voltage. Oils certified by international standards (e.g., IEC, ASTM) are preferred for stability and thermal performance.
Regular Oil Sample Testing: Periodically test oil-immersed transformer oil for key parameters such as acid value, moisture content, breakdown voltage, dielectric loss factor, and dissolved gas analysis (DGA). Immediate corrective actions should follow any abnormal results.
Use Sealed Structures or Nitrogen Protection: Modern oil-immersed transformers use fully sealed tanks to block air and moisture, slowing oxidation. Non-sealed transformers can adopt nitrogen sealing techniques to reduce oxygen contact.
Install Online Oil Filtration Devices: Continuous filtration systems remove impurities, particles, and moisture, significantly improving oil quality. Some high-end oil-immersed transformers support online oil treatment during operation.
Control Operating Temperature: Avoid overload conditions and ensure proper functioning of the cooling system (radiators, fans, etc.) to maintain oil temperature below recommended limits (e.g., 90°C), which is critical for slowing aging.
Prevent Air Ingress: During transportation, oil filling, or maintenance, operate carefully to avoid air entering the oil tank. Use vacuum oil filling techniques and gas barriers to maintain oil stability.
3. Regeneration and Treatment of Aged Oil
When oil-immersed transformer oil becomes significantly aged, consider the following treatments:
Vacuum Dehydration and Degassing: Removes water and gases from the oil to restore insulation strength.
Activated Clay Adsorption: Eliminates aging products and colored impurities to purify the oil.
Oil Regeneration Units: Utilize heating, adsorption, and filtration technologies to restore oil properties to near-new levels, offering a cost-effective and environmentally friendly solution.
4. Maintenance and Monitoring Recommendations
To prevent oil aging-related failures, establish a complete maintenance system including:
Quarterly oil test records, annual equipment inspections, oil treatment logs, and emergency incident reports.
Systematic data management improves the overall safety and reliability of oil-immersed transformers.
Oil is the “lifeblood” of the oil-immersed transformer. Its quality directly determines operational safety and service life. Through proper oil management, regular testing, and advanced protective techniques, transformer oil aging can be effectively prevented.
In today’s era of smart grids, efficient equipment maintenance not only reduces operational costs but also safeguards the long-term stability of the entire power system.
For more information on oil-immersed transformer maintenance and troubleshooting, feel free to contact us or visit our technical support platform.
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