FR3^® fluid technical details

Formulated for high-temperature performance

A transformer’s solid insulation system plays a critical role in its possible failure and in its temperature-related operating limits. The thermal class of the insulating materials constrain the transformer’s (temperature) operating limits. (The typical reference point is the average winding rise (AWR) of the transformer, which is limited to 55°C for mineral-oil designs with standard Kraft paper and 65°C for mineral-oil designed with thermally upgraded Kraft (TUK) paper for an average ambient temperature of 30°C. Put another way, historical standards were written to accommodate a thermal class of 105 for mineral-oil designs with standard Kraft paper and 120 mineral-oil designs with thermally upgraded Kraft (TUK or TUP) paper.)

As validated by standard accelerated testing method, a transformer with TUK paper and filled with FR3 natural ester fluid can operate 15°C to 20°C warmer, holding a thermal class of 140 without reducing reliability and while maintaining the same life expectancy.²

This allows for an increased load capacity for both distribution and power transformers filled with FR3 fluid, due to the possible increasing temperature rise limits. Explore the high-temperature capability of FR3 fluid compared to mineral oil.

Learn more about how FR3 fluid’s thermal capacity can provide more load capacity and resilience to your grid than mineral oil, and see how this attribute of FR3 fluid contributes to total cost of ownership.

Superior moisture tolerance

Because of its unique chemical properties as a natural ester transformer oil, FR3 fluid has an exceptional ability to remove water that is either generated by the aging of transformer insulation paper or that is present due to the intrusion of moisture into a sealed transformer. This “wicking” away of water from a transformer’s windings is due to FR3 fluid’s high saturation point and the hydrolysis process, which essentially continuously dries out the cellulose insulation paper while keeping it at its original moisture content.

Since the life of the solid insulation is often a determinant of transformer life, FR3 fluid can extend a transformer’s life by significantly reducing the degradation rate of the solid insulation. FR3 fluid’s unique properties make paper life five to eight times longer than that of the same paper immersed in mineral oil, extending the life of the transformer.¹

FR3 fluid’s high moisture saturation point also means that a transformer filled with this natural ester fluid has less likelihood of dielectric failure in cold temperatures than does a mineral-oil-filled transformer.

Transformer insulating paper end-of-life (hours)

*Paper did not read end-of-life over the duration of the test. To be conservative, extrapolation was not employed. The time to insulation end-of-life calculated using the IEEE C57.91 loading guide is used for comparison.

Learn more about how FR3 fluid natural ester transformer oil promotes extended asset life better than mineral oil, and see how FR3 fluid’s superior moisture tolerance influences total cost of ownership.

Exceptionally high flash and fire points

Classified as a Class-K, “less flammable,” and “high-fire point” fluid, FR3 fluid’s flash point is 330°C and fire point is 360°C, values that are more than two times those of mineral oil (155°C and 165°C, respectively). In fact, FR3 fluid has the highest ignition resistance of any high-fire-point dielectric fluid, including other nature ester transformer oils. Its flash and fire points also exceed those of silicone oil.

Fire point is the most relevant factor in transformer fire safety. The unique properties of FR3 fluid mean that this particular natural ester oil is the safest of the transformer oils available today. Real-world applications prove this; over decades of use, there have been no reported pool fire in any transformer filled with FR3 fluid.

Learn more about how FR3 fluid natural ester transformer oil is far safer than mineral oil, and see what FR3 fluid’s high flash and fire points mean for fire mitigation and total cost of ownership.

Best-in-class environmental properties 

With physical and chemical properties that together minimize risk to the environment and to people, FR3 fluid is derived from vegetable-oil sources that are renewable, and it is recyclable and reusable. Across its lifecycle, it is also carbon neutral (according to BEES 4.0 lifecycle analysis).

FR3 fluid does not contain petroleum, silicones, halogens, or corrosive sulfur. Formulated with >98% vegetable oil, along with proprietary performance-enhancing additives, bio-based FR3 fluid is classified as “readily biodegradable” (OECD 301 B, Environmental Protection Agency, and OPPTS 835.3100) and “ultimately biodegradable” (OPPTS 835.3110); it is nontoxic and nonhazardous in water and soil (OECD oral and aquatic toxicity test). Its physical properties also help prevent migration across surfaces and into subsurface soils in case of spillage.

FR3 fluid’s biodegradability sets it apart from silicone oil and mineral oil. Compared to these transformer-insulation-fluid alternatives, FR3 fluid requires less complex and less costly spill remediation.

FR3 fluid environmental attributes

Learn more about the FR3 fluid’s environmental advantages, and see how the superior biodegradability of FR3 fluid influences total cost of ownership.