Transformer Oil Recovery

Transformer oil recovery at the point of operation is an important part of a proactive transformer maintenance strategy. Insulating oil provides nearly 80% of dielectric strength within a transformer. It serves multiple essential functions, such as cooling and insulation of conductive components, which makes it crucial for proper transformer insulation. The quality of transformer oil directly impacts the reliability and longevity of power transformers.

Aging of Transformer Oil during Operation

As transformer oil is used, it accumulates contaminants, moisture, and oxidation products over time, all of which accelerate its aging process. The oil loses its chemical and electrophysical properties as a result of exposure to oxygen, high temperatures, sunlight, and metals (e.g. copper), which act as oxidation catalysts. The presence of water intensifies the oxidation process, further compromising the performance of oil as an insulating agent.

Transformer oil deterioration results from several contributing factors:

• Oxidation: oxygen ingress leads to formation of acids and sludge, which accelerate the aging process.
• Moisture Contamination: water content drastically reduces the dielectric strength of oil and accelerates the degradation of cellulose insulation in transformer windings.
• Thermal Stress: elevated operating temperatures increase the oxidation rate, doubling the rate of chemical reactions with every temperature rise by 50 °F.
• Metal Catalysis: copper, brass, and other metals in a transformer act as oxidation catalysts, intensifying the oil degradation.
• Electrical Stress: the presence of an electric field influences the accumulation of impurities along field lines, further reducing the insulation performance.

Oxidation leads to formation of sludge, which accumulates on active transformer components and hinders efficient heat dissipation. This sludge can cause operational issues and reduce the overall service life of a transformer. The rate of oil aging is strongly influenced by its initial quality, operating temperature, and the presence of contaminants. For instance, the oil exposed to higher temperatures and external contaminants deteriorates faster than the oil used in a controlled environment. The presence of copper, commonly found in high-voltage equipment, exacerbates the aging process by acting as a catalyst for oxidation.

Importantly, oil acidity is a key indicator of aging. An increase in the oil acid number due to the presence of low-molecular-weight acids can lead to aggressive reactions with metals inside the transformer. These reactions further degrade the insulation and reduce the dielectric strength of oil.

With proper maintenance of cooling and insulation systems, the operational life of insulation system can be extended from 40 to 60 years. Unfortunately, oil oxidation cannot be completely eliminated, but it can be controlled (slowed down) through maintenance procedures. One of the key aspects in transformer maintenance is annual oil inspection. Oil analysis allows you to assess the state of the transformer’s insulation system.

In order to stop or slow down the aging process for transformer insulation, it is essential to keep the oil in optimal condition. This can be achieved by:

• Constantly monitoring the oil condition.
• Repairing oil leaks as soon as they are detected.
• Starting to use a system (such as FLD D) for reducing the moisture content to below 10 ppm.
• Avoiding the use of moisture-laden oil from previously opened containers.
• Initiating the oil dehydration as soon as the moisture content rises to 20 ppm, or the breakdown voltage drops below 50 kV.
• Monitoring the acidity of oil and performing the reclamation of oil with the use of specialized systems (such as FLD R) before it reaches the critical level of 0.2 KOH/g.

Transformer oil recovery plants (FLD R)

Sooner or later, transformer oil degradation leads to contamination of oil and a decline in its insulating properties. The FLD R transformer oil recovery plants with the use of Fuller's Earth  restore mineral oils by removing acidic compounds, oxidation by-products, and dissolved impurities in an efficient way. This process not only extends the service life of oil, but also improves the reliability of electrical equipment.

The FLD R plants utilize an advanced adsorption process with the use of Fuller's Earth, a highly porous and chemically active material that adsorbs contaminants without the need for chemical additives. After treatment, the oil regains its initial dielectric strength, oxidation stability, and moisture resistance.

One of the key advantages of FLD R plants is the ability to reactivate the Fuller's Earth multiple times, reducing the operational costs and the environmental impact. The automated system ensures efficient oil purification with minimal human intervention, making it an ideal solution for power plants, substations, and industrial facilities.

By integrating the technology for transformer oil recovery with the use of Fuller's Earth into transformer maintenance programs, companies can significantly reduce the costs for purchasing new oil and disposing of waste oil while improving the performance and ensuring the long-term reliability of their equipment.

Economic and Environmental Benefits of transformer oil recovery

Transformer oil recovery offers a host of advantages:

• Cost Savings: eliminates the need for frequent oil change and reduces maintenance costs.
• Extended Transformer Service Life: maintains the dielectric properties of insulation, minimizing the risk of transformer failure.
• Environmental Protection: reduces hazardous waste disposal and minimizes the environmental footprint of transformer maintenance.
• Resource Optimization: allows for continuous use of valuable petroleum-based resources.