Frequently Asked Questions (FAQs)

From IEEE Standard C57.12.80-2010 IEEE Standard Terminology for Power and Distribution Transformers

3.268 natural ester: A specially refined and formulated seed-oil (vegetable oil) based dielectric fluid for insulating and cooling electrical equipment for indoor and outdoor installations, which generally conforms to ASTM D6871 when new.
 

FR3 fluid is superior to mineral oil in critical ways.

First, FR3 natural ester dielectric fluid is vegetable based, which accounts for its remarkable fire safety and superior environmental friendliness. It is an FM approved and UL classified K-class (“less flammable”) liquid with twice the flash and fire points of mineral oil, so it is less likely to start on fire. In fact, there have been ZERO reported fire-related failures of FR3 fluid-filled transformers since the product was launched decades ago. In addition, unlike mineral oil, FR3 fluid, even if ignited by an external heat source, will quickly self-extinguish when the heat sources is removed. So even though failures might still happen, fires don’t have to. Learn more about FR3 fluid and fire safety.

Second, FR3 fluid’s superior moisture tolerance compared to that of mineral oil allows it to absorb and consume dissolved moisture, slowing the aging process of insulation paper and preserving the dielectric capacity of the insulation system. This feature explains how and why FR3 fluid helps protect a transformer’s solid insulation system, extending the asset life of the transformer. Learn more about FR3 fluid and superior performance.

Third, with the standardized high temperature capability, transformers filled with FR3 fluid can operate 20°C warmer than mineral-oil filled-transformers without accelerating the aging rate of the solid insulation system. This capability provides utilities with the flexibility to (a) increase loading capacity up to 20%, (b) extend asset life, or (c) achieve a combination of both. Learn more about FR3 and grid resiliency.

Fourth, using FR3 fluid instead of mineral oil in power and distribution transformers provides significantly better environmental benefits, since it is ultimately biodegradable (according to EPA OPPTS 835.3100), readily biodegradable (according to OECD 301 B and EPA OPPTS 835.3110), carbon neutral (according to BEES 4.0 lifecycle analysis), and nontoxic and nonhazardous in soil and water (according to OECD oral and aquatic toxicity tests). Learn more about how FR3 fluid is better for the planet.

Yes. FR3 fluid is in millions of distribution and power transformer installations around the globe.

Learn more about FR3 natural ester dielectric fluid.
 

Yes. In addition to power and distribution transformers, FR3 fluid is suitable for voltage regulators, circuit breakers (switchgear), reactors, furnace transformers, rectifiers, phase-shifters, and HDVC transformers.

Learn more FR3 fluid technical details.
 

Yes. FR3 fluid has been rigorously tested 250+ times by university and commercial labs and not only complies with, but exceeds, both IEEE and IEC standards.

Of note is IEEE C57.154-1212, Standard for Liquid-Immersed Transformers Designed to Operate at Temperatures Above Conventional Limits Using High-Temperature Insulation System, which supports the increase of the temperature rise to 85°C (instead of 65°C) under continuous load (exceeding the limits of IEEE Std C57.12.00) as a rated condition for new liquid-immersed transformer designs.

Learn more about FR3 fluid and grid resiliency. Or explore the relationship between hot spot temperature and asset life for both FR3 fluid and mineral oil to see the advantages of FR3 fluid in our interactive higher thermal capacity graph.

They certainly will. FR3 fluid’s higher moisture tolerance compared to mineral oil enables the continuous drying of a transformer’s insulation paper. This can slow (although not reverse) the aging of the insulation paper, as well as preserve dielectric capacity and enhance reliability. Mineral oil keeps the moisture impregnated in the insulation paper, accelerating the aging of that paper.

Learn more about FR3 fluid and moisture tolerance.
 

Yes. OEMs can manufacture both mineral-oil-filled and FR3-fluid-filled transformers in the same facility. FR3 fluid and mineral oil are fully miscible and can share hardware equipment with very little complexity. Simply flushing operations can avoid cross contamination.

They can be, when designed for possible higher temperature rise limits; and this can result in cost efficiencies and cost savings. FR3-fluid-filled transformers insulted with thermally upgraded paper are classified as high temperature insulation system units, allowing for the increase in transformer temperature rise limits. This optimization may lead to the reduction of the total weight of the coils, as well as the cooling system, potentially reducing the total cost of materials used in the transformer.

Learn more about FR3 fluid and total cost of ownership.
 

Yes. FR3 fluid does not stop flowing inside a transformer at cold temperatures (even at temperatures lower than the IEEE C57.12.00 lowest daily average of -20°C and IEC 60076-2 lowest temperature of -20°C), and maintains breakdown voltage down to -50°C. In the unlikely event of an FR3-fluid-filled deenergized transformer being exposed to three or more consecutive days of average temperature continuously lower than the normal operating conditions, performing the very same cold-start (i.e., energization) procedures that are recommended for mineral-oi-filled transformers will be sufficient—just with the additional care of not switching taps/activating circulation pumps before temperature increases.

Unlike mineral oil, FR3 fluid keeps moisture dissolved at cold temperatures and doesn’t form cracks or voids, preserving dielectric capacity. Learn more about FR3 fluid and moisture tolerance.
 

Yes. The total dissipated energy along a period of an FR3-fluid-filled transformer may be lower than that of one designed for mineral oil. The higher thermal class of insulation paper immersed in FR3 fluid expands transformer load capacity, which is especially advantageous for peaky demand curves. During peak hours, the load losses may be higher than those of a mineral-oil-filled transformer, but only for a short period of time. Conversely, no-load losses will be lower—and they are continuous.

Learn more about FR3 liquid and flexible load capacity. Or explore the relationship between hot spot temperature and asset life for both FR3 fluid and mineral oil to see the advantages of FR3 fluid in our interactive higher thermal capacity graph.
 

Yes. The voltage for partial discharge inception (PDVI)¹ in FR3 fluid is proven by multiple different research universities and organizations to be higher than that of mineral oil, making it less prone to partial discharges. Under highly divergent field conditions, overstressed ester liquids may jump directly to “fast streamers” when tested with needle-shaped electrodes (with rounded edges sharper than 0.5 mm). However, such sharp edges are not acceptable in any well-designed and built transformer, regardless of the insulating fluid, as it may lead to high partial discharge levels. The absence of the “slow streamers” stage does not represent any disadvantage for a transformer designed to be free of partial discharge (i.e., holding a level of partial discharge lower than stringent limits).

Learn more FR3 fluid technical details.
 

FR3 fluid is >98% vegetable oil; its vegetable-oil source is 100% renewable.

Learn more FR3 fluid technical details.

There is no risk to food availability with the manufacture and use of FR3 natural ester dielectric fluid. In 2017, less than 2% of the total global consumption of transformer oil was the use of vegetable-oil-based transformer oil.

We are proud to say yes. Industry recognition includes:

• 2013 Presidential Green Chemistry Award
• 2013 Environmental Protection Agency (EPA) Design for the Environment (DfE) designation
• USDA Biopreferred Program
• EPA Environmental Technology Verification California Environmental Technology Certification
• FERC ruling (transformers retrofilled with FR3 fluid may be capitalized)

Learn more about our dielectric fluids expertise.