What’s the issue when transformers fail?

Transformers—not something most of us think about—can hold potential hidden dangers. Industry analysts report that transformer failures are common, and costly. Transformer failures can sometimes lead to events such as leaking transformer oil, rupture of the device, and transformer oil fires. These events can harm people, equipment, property, and the environment.

When transformers fail “eventfully,” our environment can suffer. If the dielectric fluid in use is petroleum-based mineral oil, transformer leaks and spills can have a harmful effect. Petroleum-based mineral oil is harmful to our environment due to certain innate properties and its relative persistence—it does not meet the Environmental Protection Agency (EPA) labeling standards for “readily biodegradable.”

In addition, while today’s mineral transformer oils are highly refined, there are hundreds of millions of gallons in existing older transformers that contain significant quantities of polynuclear aromatics. According to a U.S. Environmental Protection Agency (EPA) Environmental Technology Verification (ETV) Report*, the primary component of this mineral oil-based transformer fluid was a hydrotreated light naphthenic petroleum distillate**, ranging from 30 to 100 percent. Due to this content, such oil “was identified as an International Agency for Research on Cancer (IARC) confirmed carcinogen based on experimental data for animals.”

As a consequence, mineral oil spills can be very costly to clean up. For the utility, a single incident can mean tens of millions of dollars in clean-up and remediation costs—and that’s just what can be calculated.

*EPA 600/R-02/042
**Chemical Abstract Service (CAS) No. 6472-53-6

A costly clean-up.

Here is an example of a recent transformer incident in Fairfax County, Va. A fire caused by “an internal mechanical failure of the transformer” generated methane gas. The methane gas came in contact with the electrical fault that led to ignition of the petroleum-based mineral oil, which began to leak into the environment. To prevent and monitor potential environmental damage from the 10,000 gallons of mineral oil used in the transformer, fire-service and water-authority personnel needed to:

  1. Extinguish the fire, releasing additional hazardous materials into the environment.
  2. Establish a hazmat sector to prepare for the potential release of mineral oil and possible pollution of local water intake.
  3. Build underflow dams and deploy a set of absorption booms where streams would discharge into the body of water that leads to the Fairfax County Water Authority’s intake pipes.
  4. Conduct ongoing water sampling to ensure that no product runoff occurred.
  5. Develop a “worst-case scenario plan” should the transformer fail and the mineral oil overwhelm the fire department’s efforts to construct containment dams.
  6. Deploy vacuum trucks to collect any runoff of water, foam, and oil from the transformers.

This incident, which cost the utility close to $5 million—not including the costs incurred by the public service organizations involved—highlights the real threat mineral oil poses to the environment. It is estimated that in the United States, a mineral-oil transformer failure occurs every day. Many of these result in mineral oil leaks, killing plants and animals and contaminating water. With billions of gallons of mineral oil in use in U.S. electrical systems, the environmental risk grows every day.

This is unacceptable, because a far safer, fire-resistant, sustainable and biodegradable alternative exists: bio-based transformer fluid. In other words, it is a renewable fluid that has as its base 100 percent food-grade vegetable oil.