Filling transformers with oil – supply, treatment, testing

the role of transformer oil

Transformer oil plays a key role in the proper operation of high-power transformers. Its primary functions are effective electrical insulation of the windings and efficient dissipation of heat generated during operation. Thanks to its excellent dielectric properties, the oil penetrates all the internal spaces of the transformer, protecting it from moisture and external factors that could cause incomplete discharges and failures.

Regular inspection of the oil condition and its proper preparation before filling the transformer are the foundations of reliability and long-term operation of the equipment. Improper oil or oil contamination can lead to shortened transformer life and, in extreme cases, to costly failures and production stoppages.

Ecol – one-stop supplier of transformer oils for industry

• We operate our own Tax Warehouse, which allows the handling, production and sale of lubricating oils under the exemption or suspension of excise duty – exclusively for authorized entities. We carry out deliveries from both EU and non-EU countries, with full compliance with applicable laws, including product levies.
• We have a license from the ERO to trade in liquid fuels, which allows us to also supply oils classified under CN codes as fuels. We are registered in the SENT system and carry out transport in accordance with the Law on Monitoring the Carriage of Goods and Trade in Heating Fuels.
• We operate comprehensively – we deliver transformer oil directly to the construction site, coordinating the logistics of delivery. Upon arrival at the site, we perform laboratory tests on the oil, including measurement of breakdown voltage and water content, to guarantee the highest level of safety and quality.

We perform a wide range of physical and chemical tests, including:

• determination of water content (ppm),
• measurement of breakdown voltage (kV),
• Dissolved gas chromatographic analysis (DGA),
• Acid number and inhibitor content testing,
• Oil cleanliness assessment according to ISO/IEC standards.

DGA diagnostics allow us to detect early signs of potential transformer damage – such as incomplete discharge, overheating or pyrolysis of paper insulation – allowing us to take preventive action and minimize the risk of failure.

The process of filling a transformer with oil is a high-tech operation carried out with the use of pump-vacuum units that make it possible:

• removal of moisture, gases and solid contaminants from oil,
• heating the oil to an optimum temperature of 60°C in a way that prevents overheating,
• filling the transformer vat under vacuum (<0.5 mbar), which ensures that the space is fully and evenly filled with oil and eliminates the risk of discharge.

The process also includes:

• thoroughly check the transformer for leaks by creating a vacuum and pressure tests,
• installation of fittings and safety devices to ensure safe operation,
• protection of the interior of the transformer with dry air or nitrogen before filling,
• repeated pumping of oil in the transformer vat to remove assembly residues and ensure the highest purity (class 10/6 according to ISO 4406),
• collection of samples for final testing in an accredited laboratory.

The entire process takes 7 to 10 days, is carried out 24/7 and is tailored to the specifics of the transformer.

As part of a comprehensive service, we offer professional management of waste generated during the operation and service of transformers, such as:

• used oils,
• contaminated cleaning cloth,
• used sorbents,
• filters and other industrial waste.

We have all the required permits and issue the documentation necessary for proper waste management in accordance with current environmental regulations.