5 REASONS FOR RETROFILLING TRANSFORMERS WITH FR3

Do you need FR3 natural ester dielectric fluid in your transformers? Why would you even need to make this consideration given mineral oil has been in your transformers for years? Well, that decision might be influenced by your insurance provider and the fact that past practices are not always right for today’s applications. 

As one of the largest purchasers of FR3 fluid, SUNBELT-SOLOMON SOLUTIONS has seen Insurance Companies such as FM Global, Zurich, AIG, Travelers and others increase their awareness of fire prevention when it comes to existing transformer installations. Specifically insurance providers are taking a second look at mineral filled transformers located indoors, in close proximity to buildings or each other, the type of oil containment, and where there might be risk of spills into the environment such as installations near waterways or storm water drainage systems. These situations can be trouble should you experience a catastrophic failure or leak, unless you have preventive measures in place including Natural Ester [FR3] filled transformers, or transformers retrofilled with a natural ester fluid such as FR3.

The picture above is from a recent FR3 retrofill (replacing mineral oil with FR3 fluid) conducted by SUNBELT-SOLOMON SOLUTIONS for a nationwide Petrochemical company. The FR3 retrofill of two (2) 20MVA transformers eliminated the need for very expensive blast walls between transformers and also provided several additional benefits.

So what are the benefits of natural esters such as FR3? How about:

1.  Reduced fire risk – zero fire history

2.  Improved environmental footprint

3.  Increased transformer life expectance

4.  Optimized transformer performance

5.  Cost Implications

Reduced Fire Risk

OSHA defines a flammable liquid as “any liquid having a flash point below 93°C”. This would apply to mineral oil; however, ester-based fluids such as FR3 are much less flammable than mineral oil, it is also “non-propagating” per the National Electrical Safety Code.

FR3 is a K-class fluid with extremely high Flash and Fire Points [330℃ and 360℃] compared to mineral oil at [155℃ and 160℃]. It can drastically reduce the need for separation between transformers, other equipment, and structures. FR3 reduces the requirements for expensive options such as secondary containment, blast walls, and fire suppression systems and allows equipment to remain indoors or in close proximity to buildings, streams and waterways. NEC standards permit FR3-fluid-filled transformers to be installed indoors without fire-suppression sprinkler systems or vaults, and with minimum wall clearance of only 3 feet.

A note about retrofilling mineral oil filled transformers. As Natural Ester fluids have a Fire Point of 360°C, the Fire Point does not drop significantly during retrofills unless there is about 7.5% residual mineral oil left in the transformer windings, internals and gaskets, It does not drop out of a K Class fluid until approximately 8% residual mineral oil is left in the system (Cargill, 2018). The contractor should use the measurement of the Fire Point of the di-electric fluid after the retro-fill as a measure of the success of the retro-fill. The results of the Fire Point are greater than 300°C would be considered successful. Unsuccessful retro-fills should be evaluated for a new retro-fill. A typical retrofill would include draining, flushing and repeating prior to final fill. A properly retrtofilled transformer will benefit from the flawless fire safety history associated with FR3.

Improved Environmental Footprint

FR3 is a natural ester fluid derived from vegetable oils, like soybean. It includes additives to help with oxidation stability, operation at cold temperatures, and a green dye to differentiate it from other fluids. It is an eco-friendly fluid, designated as biodegradable by the Environmental Protection Agency offering a non-toxic alternative with 98.5 percent biodegradable content, and free of petroleum, halogens, sulfurs, and silicones.

If a spill were to occur, the environmental impact is minimal and remediation costs are lower since the fluid is higher in viscosity, biodegradable, non-toxic, and non-hazardous in soil or water. Per EPA SPCC Bulletin 1724E302, secondary containment could be a simple earthen berm and Biodegradation is a legitimate water/soil remediation tool. (Cargill, 2016)

FR3 has excellent miscibility and compatibility with conventional mineral oil and high temperature hydrocarbon fluids (i.e. R-Temp? fluid). Important Note - FR3 fluid is not miscible with Silicone and should not be applied in transformers previously containing silicone.

Increased Life Expectancy

Moisture and heat are a transformers two worst enemies. Moisture in dielectric fluid such as mineral oil can contribute to low dielectric strength and cause dielectric failure. Transformers do produce water over time as part of their normal operation which is a product of internal gases produced. 

As a mineral-oil-filled transformer operates, internal temperatures increase and moisture migrates from the paper insulation into the fluid, returning back into the paper when the temperature reduces. FR3 and natural esters have a unique ability to draw out and retain this moisture at a rate of 10x more than mineral oil while maintaining dielectric strength. Hydrolysis is the term where natural ester fluids will “dry out” the transformer insulation where most water is held. In this process the natural ester fluids absorb free water, capture it, and turn it into long-chain fatty acids keeping paper insulation dry.

The above hydrolysis slows down the aging process of cellulose paper, thus increasing the longevity for transformers and other equipment. It is known that the high water saturation point of FR3 can extend the life of an insulation system by five to eight times.

Optimized Transformer Performance

With FR3’s ability to preserve cellulose paper insulation systems, even at elevated temperatures, transformers can be designed to operate up to 20℃ higher than standard mineral oil-filled units. This allows kVA ratings to be increased accordingly, improving overall performance and in cases eliminating the need to upgrade or replace units. Should a retrofill be performed and increased kVA is desired, higher temperature gaskets are required such as Silicone or Flouropolymer (Viton) composition. Should a transformer be in service for more than 20 years prior to a retrofill, it is highly suggested to replace all gaskets regardless. Transformers operated at higher temperatures should have all gaskets replaced after 10 years of operation.

Cost Implications

Taking a proactive approach to loss prevention and standardizing on Natural Ester Fluids like FR3 is a step in the right direction to mitigating potential catastrophes while supporting the environment, communities and budgets. Mitigating potential catastrophes can be directly proportional to lower insurance and liability costs.

Because the use of natural ester fluid has been proven to extend the insulation life of assets as described above, the Federal Energy Regulatory Commission FERC has ruled that all costs associated with the conversion to natural ester fluids (fluid, labor, equipment) may be capitalized. This is a big financial plus that eliminates the need to increase or justify the expenses as part of ongoing O&M Budgets.

The cost of natural and synthetic ester fluids should be a consideration, compared to mineral oil. Natural ester fluid cost, based on volume, is approximately double the cost of mineral oil. Synthetic ester fluid is approximately double the cost of natural ester. 

In closing SUNBELT-SOLOMON SOLUTIONS recommends FR3 retrofills:

• For locations in environmentally sensitive locations near waterways and parks, in close proximity to buildings, and transformers located within buildings.
• For overall reliability of critical loads
• To assist with removal of water from paper insulation
• For transformers loaded to nameplate ratings to gain additional capacity
• To extend the life expectancy of transformers

For more information, check out these links

https://www.solomoncorp.com/why-you-should-consider-making-the-switch-from-mineral-oil-to-fr3

https://www.cargill.com/bioindustrial/fr3-fluid/why-fr3-fluid