Just The Facts: Fr3 Oil

July 28, 2015

Transformer oils serve two distinct purposes. The first is to provide electrical insulation in power transformers, the second is to act as a coolant to dissipate heat. In the past, transformer oil was generally paraffin-based or naphtha-based, a petroleum derivative. In light of continually evolving environmental concerns, Cooper Power Systems, in partnership with Cargill, looked to create an alternative with benefits greater than traditional mineral and dielectric coolant alternatives. The result is FR3, a natural ester solution derived from vegetable oils. Cargill has since purchased full rights to FR3 from Cooper. Considered a superior fluid to mineral and other dielectric coolants, FR3 can prevent and quench electrical discharges, provide electrical insulation, and suppress corona and arcing. Considered ultimately biodegradable (98.5%) by the Environmental Protection Agency, FR3 is free from halogens, silicones, sulfurs and petroleum. The self-healing natural ester fluid will also not leave a permanent conductive trace and has the ability to maintain dielectric strength at low temperatures.


Concerns about the flammability of petroleum-based derivatives like naphtha in part prompted the creation of FR3. The derivative vegetable oil offers 100 percent fire safety, making it a secure choice for transformers located next to buildings, underground or indoor. Unlike petroleum, which is a non-renewable resource, the FR3 vegetable oil derivative FR3 is renewable, non-toxic, recyclable and carbon neutral. The natural ester solution of FR3 is also FM Global Approved and classified as a less-flammable dielectric liquid alternative by Underwriters Laboratories.

FR3 Better Protects Insulation Paper

Extended use of mineral oil can result in the breakdown of the insulating paper over a period of time. The non-corrosive properties of FR3 have the ability to protect insulation 5-8 times longer, a major source in determining the life of an asset. FR3 works by drawing moisture away from the insulating paper during aging. As a result, paper quality increases and load-ability grows. Acids formed in the vegetable oil-based FR3 are non-corrosive and maintain voltage breakdown with up to 430 ppm of water. FR3 also does not require reprocessing.

Benefits of FR3

  • Increased paper quality by wicking water away
  • Superior benefits to mineral oil and other dielectric coolants
  • Self-healing coolant properties
  • Load-ability enhanced up to 20%
  • Slowed time for asset replacement
  • Reduced routine maintenance
  • Extended life of Kraft Paper
  • Ability to handle higher temps
  • Meets ICE and IEEE standards
  • Increases allowable Hottest Spot Temp by 15°C
  • Improves fire safety with high fire flash points
  • Lacks corrosive byproducts
  • Extends insulation and transformer life
  • Offers safety in power and distribution transformers through 420kV
  • Results globally tested in 250+ tests