Utilities Turning to Vegetable Oil-based Transformer Fluids

By Patrick McShane, Cooper Power Systems

Some parts of the Gulf Coast region may never be the same after the devastation caused by hurricanes Katrina and Rita. Flood waters destroyed electrical distribution equipment, along with most everything else, in several low-lying areas. To help rebuild the infrastructure of these areas, local utilities are working to install new equipment with added long-term environmental benefits. One specific supplier, Cooper Power Systems, has increased production capacity of its Envirotran EF transformers filled with soy-based Envirotemp FR3 fluid. The FR3 fluid is formulated for use in distribution and power transformers where its environmental, fire safety, chemical and electrical properties are advantageous.

During Hurricane Katrina, transformers were damaged, leading to leakage and exposure of the transformers’ contents into the environment. Envirotran EF transformers use a bio-based transformer oil made from soybeans that can minimize the damaging impact that hazardous materials may cause in disaster-vulnerable areas. Unlike other transformer fluids, FR3 fluid does not contain petroleum hydrocarbons, silicones or halogens that could potentially harm the environment.

Envirotemp FR3 has two key features that make it more environmentally safe than other transformer fluids in disaster-vulnerable areas: rapid biodegradation rate and non-toxicity. Biodegradation can take place when there are adequate amounts of water, oxygen, organisms and heat as FR3 fluid can quickly and thoroughly biodegrade in both soil and aquatic environments. Inside a sealed transformer, these elements do not exist together in sufficient quantities to promote biodegradation. Outside a transformer, FR3 fluid biodegrades rapidly into what essentially amounts to carbon dioxide and water. In 21 days, mineral oil biodegrades just 25 percent while FR3 fluid biodegrades in excess of 99 percent. Also, if gravel is used around outdoor transformers, vegetable oil-based FR3 fluid is less likely to percolate through earth and gravel, thus impeding transmission to groundwater.

Because of its unique formulation, Envirotemp FR3 fluid is not subject to the Federal Regulation of Used Oils. Instead, FR3 fluid is covered by the Edible Oil Regulatory Reform Act-making it a potentially more favorable option for utilities that are considering environmental risk and regulations.


FR3 fluid has been tested in accordance with standard aquatic toxicity methods.
Click here to enlarge image

FR3 fluid has also been toxically tested by third parties in accordance with standard aquatic toxicity testing methods that are defined by the Organization for Economic Co-operation and Development (OECD) and Environment Canada. The Environmental Protection Agency (EPA) has issued an affirming statement through the Environmental Technology Verification Program (ETV), deeming FR3 “readily & ultimately biodegradable” per EPA.

All of that points toward why Glacier Electric Cooperative, based in Cut Bank, Montana, began using Envirotemp FR3 fluid as a transformer coolant in 2004. Glacier Electric’s choice of this fluid was due to its commitment to the environment, as environmental stewardship is essential when servicing one of the country’s most environmentally sensitive areas in Glacier National Park.

In another instance, Steuben County in Northeastern Indiana is the home of 101 natural lakes, so transformer proximity to waterways has always been difficult to avoid. Due to the sensitivity of those areas, Jamie Shields of Steuben County REMC has been selecting transformers filled with FR3 fluid because of its biodegradable ability within waterways. With the addition of Envirotemp FR3 fluid filled transformers, Steuben County’s 101 lakes and wildlife are safer should any transformers be damaged and caused to leak.

Besides those two examples, utilities in low-lying cities across the United States have filled more than 15,000 transformers with Envirotemp FR3 fluid. FR3 fluid is also available in North and South America, the European Union, Central America, the Caribbean, Australia, New Zealand, and Korea.

Additional Benefits

Petroleum is the base fluid for traditional mineral oil-based transformers, which represent the majority of transformers damaged or destroyed in the states affected by Hurricane Katrina. Reports indicate that Hurricane Katrina knocked out 90 percent of the petroleum production in the Gulf region and a significant portion of the nation’s refining capacity. Even a partial conversion by utilities to the use of bio-based oil in transformers could reduce demand for petroleum at a time when supply is expensive and lacking. Envirotemp FR3 fluid is also a renewable energy source grown domestically. Twenty-nine U.S. states have a significant soy-growing constituency.

Tipmont REMC, an electrical provider to over 20,000 sites in west central Indiana, uses Envirotemp FR3 fluid, rather than petroleum oil, in all of its overhead electric transformers. Along with environmental protection, one of the main reasons for Tipmont REMC changing to transformers that use FR3 fluid is the benefit to the agricultural industry. There has been a long tie between electric cooperatives and agriculture, thus using the soybean-based fluid to support and benefit the agricultural economy.

Dielectric coolants with fire points of 300 degrees Celsius or higher can qualify as a Less-Flammable Liquid per the National Electrical Code (NEC). Envirotemp FR3 fluid has the highest flash fire point (360 degrees Celsius) of any less-flammable fluid currently on the market. Its fire-resistance qualities and high fire point are traits that benefit customers by protecting them against the harmful effects of transformer failure-caused fires. This feature greatly reduces the likelihood of a disastrous fire occurring in association with a failed transformer in highly populated areas. Based on electrical fire code regulations and nationally recognized testing laboratory certifications, FR3 fluid filled transformers can be installed indoors and outdoors, adjacent to buildings, walkways, or on roof tops, typically without additional fire safety requirements.

Alliant Energy experienced a low current fault in an underground cable beneath a row of 13.8-kV metal-clad switchgear. Because the breaker did not trip, the fault continued to burn, eventually knocking out power to a large section of downtown Dubuque, Iowa. Fortunately, only the switchgear and cable were damaged. However, because there had been magnesium on the cable, the fire could be seen for miles, catching the attention of the media and giving the event extensive negative coverage. Alliant recognized the fire could have occurred on the substation transformer end of the circuit and chose to participate in a beta test of Envirotemp FR3 transformer coolant at several substations, including the retrofilling of a 1957 vintage step-up transformer. The decision was based on the fire and environmental safety benefits of the fluid.

FR3 fluid can help keep utility capital spending costs down and reduce fire insurance requirements. Typically, risk management companies and insurance groups do not require expensive fire safeguards, such as deluge systems, with FR3 fluid.

Finally, FR3 fluid extends transformer paper insulation life five to eight times per testing based on IEEE standards. The increased insulation life translates to extended and enhanced transformer life, and the ability to carry higher loads during peak demand periods without leading to premature insulation failure.

Conclusion

Because of its proven environmental, fire safety and performance enhancing characteristics, FR3 fluid is being used in more new transformers, retrofilling applications for transformers, and other fluid-filled distribution and power equipment. Purposes for Envirotemp FR3 fluid have expanded into a variety of other equipment, including power transformers and reactors, voltage regulators, sectionalizing switches, transformer rectifiers, electromagnets, and voltage supply circuits for luminaries.

McShane is global products manager for Cooper Power Systems.

EPRI Solutions Pinpoints Cause of Transformer Failures

Engineers at EPRI Solutions in early April released information saying they have conclusively identified the root cause of a number of recent failures in large power transformers owned by electric utilities. These and similar failures, reported in several countries around the world, have puzzled owners and manufacturers alike, particularly since many of the problems have occurred in relatively new equipment.

Many of the transformer failures are attributable to corrosive sulfur contamination in the electrical insulating oils, according to EPRI Solutions’ senior technical director and project manager Nick Abi-Samra, a leading expert in root cause failure analysis for power systems and components.

“We’ve found that the failures are not confined to any certain transformer manufacturers or oil suppliers. Even though the transformer oils have passed industry specifications and standard tests, many of them contain thermally unstable sulfur-bearing compounds,” Abi-Samra said. “These compounds can be converted to corrosive sulfur as the equipment operates under heavy load, so generator step-up transformers and other transformers that operate consistently at high temperatures are at the greatest risk of failure.”

The existence of corrosive sulfur in transformer oil was first reported many decades ago, but was thought to have been eliminated through improved industry standards and detection methods. “The prevalence of new failures indicates a strong need for near-term practical research to diagnose and prevent expensive damage to utility transformers,” stated EPRI Solutions Vice President Arshad Mansoor. “We are supporting a major new collaborative R&D project through our parent organization, the Electric Power Research Institute (EPRI), to conduct a comprehensive investigation on this critical industry issue.”

In the meantime, EPRI Solutions experts have developed a number of new tests to identify and deal with transformers and reactors that have a high likelihood of failure due to corrosive sulfur. EPRI Solutions is currently working with its utility clients around the world to mitigate the costly impacts of corrosive-sulfur damage, based on these latest findings.

More information on EPRI Solutions’ capabilities in transformer inspection and preventative/predictive maintenance is available via the company’s website, www.eprisolutions.com.

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