Reinhibiting Oil Filled Transformers

Optimal Performance and Longevity

At RESA Power, we offer comprehensive transformer services to ensure the longevity and optimal performance of your oil-filled transformers. Our team of experienced technicians is equipped with the knowledge and expertise to provide effective solutions for your transformer maintenance needs.

Get a Quote for Reinhibiting Oil Filled Transformers


Get a Quote for Reinhibiting Oil Filled Transformers

Get a Quote

Benefits of Oxidation Inhibitors in Power Transformers 

Oxidation inhibitors play a crucial role in power transformers by preventing the oxidation of the transformer oil and the formation of harmful byproducts. This helps to extend the lifespan of the transformer and improve its overall performance. 

The benefits of oxidation inhibitors in power transformers include increased operational reliability, reduced maintenance costs, and improved energy efficiency. One of the key advantages of using oxidation inhibitors is their ability to inhibit the formation of sludge and deposits in the transformer oil. Sludge and deposits can lead to insulation breakdown, reduced heat transfer efficiency, and increased risk of equipment failure. By preventing the oxidation process, inhibitors help to maintain the oil’s stability and cleanliness, ensuring optimal performance of the transformer.

Furthermore, oxidation inhibitors also help to minimize the degradation of cellulose insulation in power transformers. Cellulose insulation is commonly used in transformers to provide electrical insulation. However, over time, oxidation can cause the cellulose to deteriorate, leading to reduced insulation properties and an increased risk of electrical faults. By inhibiting oxidation, these inhibitors help to preserve the integrity of the cellulose insulation, thereby extending the lifespan of the transformer.

In addition to these benefits, oxidation inhibitors also contribute to improved energy efficiency in power transformers. Oxidation reactions generate heat, which can lead to increased operating temperatures in the transformer. By preventing oxidation, inhibitors help to reduce heat generation and maintain lower operating temperatures. This not only improves the energy efficiency of the transformer but also reduces the need for cooling systems, resulting in cost savings. 

Overall, the use of oxidation inhibitors in power transformers offers numerous benefits, including increased operational reliability, reduced maintenance costs, improved energy efficiency, and extended lifespan. These inhibitors play a vital role in ensuring the optimal performance and longevity of power transformers.

Maximizing Transformer Lifespan through Reinhibiting and Proper Inhibitor Maintenance

By prioritizing the reinhibiting process for transformers and maintaining appropriate levels of oxidation inhibitors, you can significantly increase the lifespan of your transformers. 

Extensive data analysis indicates that transformer owners who diligently monitor and maintain proper inhibitor levels can extract substantially more operational hours from their transformers. 

This is a crucial advantage, as it reduces the need for frequent replacements and costly downtime, ultimately optimizing the efficiency and cost-effectiveness of your transformer assets. By investing in regular reinhibiting services, you can safeguard your transformers, ensure their optimal performance, and maximize their longevity.


It is important to assess the type of oil in a unit before determining if an inhibitor is necessary.

RESA Power Recommends

In the case of type I oil (uninhibited), we won’t always recommend the use of an inhibitor. Instead, we will carefully evaluate the oxygen levels present. This approach ensures that we provide tailored and appropriate solutions for each specific case, optimizing the performance and longevity of the unit. By considering the unique characteristics and requirements of each transformer, RESA Power delivers targeted recommendations that align with the highest standards of quality and effectiveness.

Protect Your Transformers with Oil Inhibitor Services

Are you aware of the potential dangers of sludging caused by oxidation in insulating fluid-filled transformers? At RESA Power, we offer Oil Inhibitor services that address this critical issue. Sludge, often considered as a transformer killer, may develop over time in uninhibited or under-inhibited type 2 fluid filled transformers and can degrade the dielectric strength of the fluid and ultimately result in catastrophic failure of the unit.

Our Oil Inhibitor service combats this problem by utilizing BHT (butylated hydroxytoluene) in the appropriate volume and dispersion. 

This proactive approach effectively attacks free radicals, protecting the molecular structure of the insulating fluid from the harmful effects of oxygen ingress and other contaminants.

Don’t let sludging compromise the performance and longevity of your transformers. Trust RESA Power’s Oil Inhibitor services to safeguard your vital electrical assets.

Understanding Transformer Oxidation Inhibitors

Most mineral oil dielectric fluids contain an added oxidation inhibitor, a chemical additive that acts as a preservative. The primary purpose of the inhibitor is to prevent oxygen from reacting with the oil, thereby slowing down the aging process of the oil and solid insulation. 

Two commonly used oxidation inhibitors in transformer oils are:

  • 2,6-ditertiary-butyl para-cresol (DBPC)
  • 2,6-ditertiary-butyl phenol (DBP), the latter also known as butylated hydroxytoluene (BHT)

Maintaining Optimal Inhibitor Concentration

At RESA Power, we recognize the importance of maintaining an adequate inhibitor concentration in transformer oil. Through Fourier Transform Infrared (FTIR) spectroscopy, we determine the total concentration of oxidation inhibitors in transformer oil.


An inhibitor concentration of less than 0.1% (by weight) is considered unacceptable as it provides insufficient protection against oxidation.

RESA Power Recommends

Should the inhibitor level drop below 0.1%, we recommend re-inhibiting the oil and adding inhibitor to bring the concentration back up to 0.3%.

Reinhibiting Process

Reinhibiting is a critical step in ensuring the continued protection of your oil-filled transformers. Our team of experienced technicians specializes in the reinhibiting process, combining technical expertise with state-of-the-art equipment.

Following the purification process (dictated by oil sample results), our technicians add a concentrated solution of 2,6-di-tert-butyl-p-cresol (DBPC) inhibitor to the oil stream returning to the transformer, utilizing our formula to add the correct amount required.


The final concentration of inhibitor in the oil should be 0.3% (by weight). This complies with standards IEC 60296, ASTM D3487, AS1767.

RESA Power Recommends

If the acid number of the oil exceeds 0.06 mg KOH/g or the interfacial tension (IFT) drops below 31.9 mN/m, additional oil reclamation and reinhibiting may be necessary.

Choose RESA Power for Reinhibiting Oil Filled Transformers 

When it comes to ensuring the longevity and optimal performance of your oil-filled transformers, RESA Power is the ideal partner. Our expert team, state-of-the-art equipment, and commitment to excellence make us a reliable choice for all your transformer maintenance needs. Contact us today to learn more about our oil inhibitor transformer services and how we can help you enhance the efficiency and reliability of your transformers.

Get a Quote for Reinhibiting Oil Filled Transformers

Get a Quote

Learn More About RESA Power Services


Electrical Testing & Diagnostics Maintenance & Repair Acceptance Testing Engineering Studies

Learn More


Maintenance & Assembly Coil Rewinding Oil Testing Services New & Used Transformer Sales

Learn More


Remanufacture & Custom Build of Electrical Infrastructure & Equipment

Learn More


Broad Inventory of Electrical Equipment & Components Including Older Vintage & Hard-to-Find

Learn More


RESA Power has more than 40 service locations across the United States and Canada, including a transformer oil testing laboratory and specialty distribution centers to ensure our customers’ critical power systems are safe, reliable, and operating at peak efficiency. Click on the service center nearest to you for more information.