Protect the paper, improve overall grid reliability.
The number one factor that has the greatest impact on the life of a transformer is the insulation paper. FR3 fluid is proven to protect the insulation paper 5-8 times longer than mineral oil. That extends asset life, reduces total cost of ownership and improves grid reliability.
Paper produces water as a by-product of thermal aging which acts as a catalyst for continued degradation. While thermal aging cannot be avoided, it can certainly be slowed down. How can you do that with a dielectric fluid?
The answer lies in FR3 fluid’s unique chemistry. Because mineral oil is hydrophobic, most water stays in the paper. However, Envirotemp™ FR3™ fluid is comparatively hydrophilic, so water is absorbed by the fluid or wicked away from the insulation paper. At room temperature, FR3 fluid has 10 times the water saturation level as mineral oil (FR3 fluid can dissolve over 1000 mg/kg of water before becoming saturated compared to 60 mg/kg for mineral oil at 20°C.)
Numerous published aging and electrical verification studies of cellulose and FR3 fluid provide surprising observations compared to the same studies in mineral oil (see aging comparison chart). Cellulose was observed to last from five to eight times longer in FR3 fluid than in petroleum-based mineral oil, confirmed by multiple studies.
Higher temperature capability with FR3 fluid further protects insulation system
Research has confirmed that the cellulose insulation is more protected from thermal degradation in the FR3 fluid because the fluid has 20 degrees more margin of thermal ability than mineral oil.
Thermally upgraded cellulose insulation in FR3 fluid has a transformer hot spot capability of 130°C compared to 110°C for the same cellulose in mineral oil. Within a transformer when the insulating paper ages, water molecules are released from the insulation which accelerate further degradation of the cellulose. However, with FR3 fluid, a hydrolysis reaction occurs whereby a molecule of water is converted to a non-reactive, long chain, free fatty acid thus absorbing the water molecule into the carbonyl structure of the natural ester. These fatty acids have no impact on the performance of the fluid or transformer. Also, they are non-corrosive as compared to acids generated with mineral oil.
With a FR3 fluid-filled transformer, the water volume (ppm) allowed before reaching saturation and acid counts will be higher. That’s not a bad thing – that’s normal for FR3 fluid compared to a mineral oil transformer. By being able to absorb the extra water produced as part of the thermal aging process and having a higher water saturation point, FR3 fluid protects the insulation paper (essentially ‘self drying’) thus extending the asset life and helping improve the grid reliability. FR3 fluid can extend the insulation life of new transformers or the residual insulation life in a retrofilled transformer.
Application of Natural Ester Insulating Liquids in Power TransformersRead paper (PDF)
Interaction mechanisms of natural ester dielectric fluidRead paper (PDF)
Review of Kraft paper natural ester fluid insulation system agingRead paper (PDF)
Long gap breakdown of natural ester fluidRead paper (PDF)
ICHVE 2012Read paper (PDF)
Lightning impulse testing of natural ester fluid gaps and insulation interfacesRead paper (PDF)