Transformer Oil Treatment – Vacuum Dehydration Unit DRYCORE
The vacuum dehydration unit DRYCORE is a specialized system designed for the cleaning, degassing, and drying of transformer oil. This vacuum dehydration unit efficiently removes physical contaminants, dissolved gases, and moisture from electrical insulating oils, ensuring that transformers maintain their insulation and cooling properties at optimal levels.
Oil Cleaning Process
Oil cleaning is a process that removes or reduces physical contamination using mechanical and physical methods such as filtration, drying, and degassing. In most cases, a combination of filtration and vacuum degassing is employed. The vacuum dehydration unit is capable of removing solid particles larger than 0.2 μm and eliminating most of the water and gases dissolved in the oil. This process is usually sufficient to restore low dielectric breakdown voltage caused by solid contaminants and high moisture content, which are common in heavily used oils. Regular scheduled maintenance of transformer oil is essential to preserve its insulating and heat-dissipating properties.
Moisture Risks in Transformers
The risk of excessive moisture in transformers must not be underestimated. Moisture in insulation leads to three main problems: reduced dielectric strength, accelerated aging of solid insulation, and decreased bubble point temperature. Moisture enters transformers primarily from atmospheric humidity and water released from solid insulation and oil during aging. Water dissolves in transformer oil in small quantities, and its solubility depends on both temperature and chemical composition.
During operation, moisture migrates from the oil into solid insulation. The rate of this migration is slow and depends on several factors, including temperature. Maximum moisture saturation in oil depends on factors such as aromatic hydrocarbon content and oil temperature, whereas in solid insulation, temperature has little effect. Because the equilibrium of water distribution between oil and insulation follows equilibrium laws, the constantly changing temperature of operating transformers prevents a stable balance. As the oil temperature rises, moisture moves from solid insulation to oil, and when the temperature drops, moisture returns to the insulation.
Operation of the Vacuum Dehydration Unit
When transformer oil reaches high moisture levels, the transformer is disconnected, and a high-performance vacuum dehydration unit is connected. The DRYCORE unit performs multiple functions: heating, pumping, purification, degassing, and moisture removal. It can also evacuate air and gases from transformer tanks during servicing or repair, ensuring safe operation.
The degassing process works as follows: oil is heated to approximately 194°F (90°C) and then treated under vacuum conditions. This procedure removes residual water and dissolved gases, bringing transformer oil within compliance of technical standards. After treatment with the vacuum dehydration unit, oil achieves the following parameters: volumetric gas content ≤0.1% and mass moisture content ≤10 ppm.
The DRYCORE vacuum dehydration unit includes an operator workstation, equipped with all necessary measurement instruments and control systems. It has an automated operation mode that ensures safe and efficient operation without constant human intervention. The system is versatile, suitable for transformers of any size or age, and can be applied to on-load tap changers (OLTC), bushings, and high-voltage switches.
Key advantages of the DRYCORE vacuum dehydration unit include:
- Efficient removal of solid particles, moisture, and dissolved gases.
- Restoration of dielectric strength.
- Automated control and built-in safety features for operator protection.
- Universal applicability for transformers of different sizes and ages.
The vacuum dehydration unit DRYCORE is a vital tool for maintaining transformer oil quality, preventing insulation degradation, and extending the lifespan of high-voltage equipment. By combining heating, filtration, degassing, and dehydration in one system, the unit ensures comprehensive oil treatment and reliable transformer operation.