Oil Purification

Oil purification should be carried out on a regular basis during the operation of high-power transformers. During operation, water, oxidation products, and mechanical impurities accumulate in the oil.

With the development of modern technology, the requirements for transformer oils have become more stringent. The service life of a transformer directly depends on the condition of transformer oil.

Transformer Oil Production and Characteristics

Transformer oils are typically high-purity mineral oils with low viscosity. These oils are used not only in power transformers, but also in oil circuit breakers and reactor assemblies. The oil insulates the energized parts and naturally cools the heated components. The higher the quality of transformer oil, the longer the transformer will function before the need for maintenance arises.

The requirements for oil cleanliness remain high, as the operational life of a transformer depends directly on the proper functioning of its insulation system, which relies heavily on the quality of transformer oil. Even if the transformer is initially filled with high-purity, homogeneous oil, oxidation products and contaminants will accumulate in the oil after a few months of operation. If water and oxygen are present in the oil, the oxidation process begins.

Contaminants can include:

• Metal oxides
• Alcohol oxides
• Aldehydes

These contaminants result from the oxidation of solid equipment parts. Dirt settles on the insulation, causing the oil to thicken and thereby significantly impairing its cooling properties.

In order to prevent such undesirable consequences, transformer oils undergo deep purification using several methods.

Methods of Transformer Oil Purification

Below are some of the most commonly used methods:

1. Filtration: this method removes solid contaminants from the oil by running it through filters made of paper or synthetic materials. It’s effective for removing large particles, but doesn’t address moisture or gases.
2. Centrifugal Separation: using centrifugal force, this technique separates heavier contaminants, like water and sludge, from the oil. It’s effective for removal of water and solids, but not gases.
3. Dehydration using Absorbents: moisture is removed with the use of materials such as silica gel or molecular sieves. This method is effective for eliminating water, but not gases or solid particles.
4. Ion Exchange: this method removes acidic ions and salts with the use of resins. It’s effective for treatment of oils with high acidity, but not for removing solid particles or gases.

Initially, oils undergo preliminary purification methods that remove solid contaminants and water. The next stage involves deeper purification achieved through vacuum treatment, known as thermophysical cleaning. Only after the completion of these procedures,  the main purification of transformer oil is carried out through various chemical treatments.

Why Oil Purification is Important

Transformer oil purification enables the following:

• Restoration of the dielectric properties of oil. Contaminants and moisture significantly impair the insulating properties of the oil, potentially leading to breakdowns and short circuits.
• Removal of oxidation products and mechanical impurities. During operation, the oil accumulates oxidation products, metal particles, and other contaminants that increase its viscosity and degrade its heat transfer properties.
• Reduction of oil change costs. Oil purification is much more cost-effective than complete oil change with the required operational properties maintained.

Removal of mechanical impurities and water from the oil is necessary to ensure its dielectric properties and to prevent corrosion of the transformer's internal parts. Routine purification improves equipment efficiency and serves as a cost-effective alternative to frequent oil changes.

Operating Principle and Benefits of FLD D Unit

Over time, transformer oil becomes contaminated with mechanical impurities, water, and oxidation products, which degrade its properties and reduce the transformer's lifespan. In order to restore the original properties of the oil, purification processes are performed using specialized units such as the FLD D.

Transformer insulating oil should be free of moisture, dissolved gases, and particles that accumulate as the oil ages. This is particularly important for transformers operating under high loads and exposed to external factors such as temperature fluctuations, humidity, and contamination. Even some new oils may require treatment to reduce their content of impurities to acceptable levels. We are a manufacturer capable of customizing industrial units in accordance with the best available solutions.