The insulating oil, typically found in high voltage equipment (transformers, circuit breaker, cables, bars,
turbines among other elements), is a low viscosity and transparent mineral used mostly in electrical
insulation and thermal purification systems to protect solid insulation against the airflow and moisture.
This substance has high chemical stability, usually maintaining its fundamental characteristics for a long
time without modifying them; however, with time and continuous use, it causes aging and degradation.
The dielectric properties of oil depend directly on the level of its contamination, only detected by
performing specialized tests at certified laboratories. Depending on the results and its interpretation, the
process: Filtration, Regeneration, or change, is selected.
Filter, Purification, and Thermo-Vacuum is the best way to treat
moisture content, dielectric strength, and when the saturation percentage is outside normal parameters.
By removing the moisture on time, the oxidation process and degradation due to the formation of sludge
will begin.; eventually clogging the cooling ducts resulting in reheating the windings and shortening the
life of the transformer.
PROJETO GROUP provides the equipment that uses the CMM system for degassing, dehydration, and oil

Oil Regeneration

We performed Oil regeneration when the neutralization number is >=0.06, and the interfacial voltage is <=27.9 and color >=4.0. With our Fuller Ground Ultra Clear 30/60 equipment, the oil gets to its anilinepoint (a temperature where the oil becomes a solvent and the sludge dissolved); then, recirculate the oil. As a result, the same oil is responsible for cleaning the coils, flanges, core, switch, among others. Once finished, the oil is passed through the Fuller Earth tanks to remove the vast majority of decomposition products, polishing and restoring the oil to its new characteristics.

Oil Change

The Oil Change is the recommendation when the number of neutralizations, interfacial voltage, and color is outside the allowed parameters, and the customer, due to time constraints, cannot perform the regeneration.

The Oil Change process consists of emptying all the oil, removing the high voltage insulators, and washing the windings with new oil. Then the sludge that may be obstructing the cooling ducts should be removed, and the packing changed then should fill it up with fresh oil.

Transformer Maintenance
Off-Line or De-energized Power Transformers

It is carried out in a preventive or corrective manner, usually when there is a transformer with advanced oil degradation, and the insulating paper has a high percentage of water. Also, when there are no appropriate valves or the existing ones are inadequate for hot treatment and or when the transformer can Be de-energized without affecting production.

As a result of our extensive experience, we have developed three groups of maintenance formulations based on the recommendations of the oil analysis diagnosis :

  • Thermo vacuum treatment plus inhibitor addition.
  • Insulation regeneration without drying.
  • Insulation regeneration with drying.

Leakage correction, silica gel change, checking of drive/control devices, and oil level reset.
Drying of the insulating elements, degassing and oil inhibition, pressurization.
Regeneration and delodification of the paper-dielectric oil system.
Electrical and insulation tests on site.
Connection setting and hot spot correction


Avoid spillage and waste of hydrocarbon products.
Increase the life of the transformer.
Maintain the physicochemical properties of the oil and prevent sludge formation.
Diagnose the insulation-electrical system.
Avoid damage to contact points.
Increase transformer reliability.

Online Transformer Maintenance

Testing of Power Transformers Online or Energized Must be performed in energized transformers with a volume greater than 300 gallons to decrease the water content in the oil, which is one of the main enemies of the insulating paper. The regeneration of insulating dielectric oil is performed, which improves its physical-chemical properties, thus preventing sludge formation that can obstruct the transformer’s cooling ducts.

Drying of the active part and the oil with an energized transformer:

Reception of the transformer to personnel designated by the client.
Initial oil sampling (ADFQ).
Total oil treatment of the transformer (specialized equipment).
Addition of inhibitor.
Final oil sampling (ADFQ).
Delivery of the transformer to personnel designated by the client.
Presentation of the final work report, including oil testing protocol.

Insulation Oil Regeneration Without Drying

Reception of the transformer to a customer representative, initial inspection, and maintenance
Initial oil sampling (ADFQ)
Regeneration of the insulation system – oil paper (specialized equipment)
Addition of inhibitor.
Final oil sampling (ADFQ)
Presentation of the report of what has been done, including oil testing protocol


Carry out the maintenance of the transformer WITHOUT NEED TO REMOVE IT FROM SERVICE.
Increase the life of the transformer and oil
Maintenance helps prevent unwanted service output from the transformer.
Improve the physicochemical characteristics of dielectric oil.
Achieve proper drying or regeneration of insulating paper.
Environmentally friendly.