Last month, the U.S. Department of Energy (DOE) published a final rule establishing new energy-efficiency standards for distribution transformers. The standards specifically apply to liquid-immersed and medium-voltage, dry-type distribution transformers but not to underground mining distribution transformers.

The new rule could boost the cost of liquid-immersed transformers by up to 12%, yet should lower electrical losses by as much as 23%. Furthermore, it could raise the cost of medium-voltage, dry-type transformers as much as 13%, but should reduce electrical losses by up to 26%.

“With approximately 41 million transformers serving the nation's electrical distribution systems, any improvement in efficiency is going to lead to significant energy savings, and we are glad to see this new standard,” says Thomas R. Kuhn, president of the Washington, D.C.-based Edison Electrical Institute (EEI), which represents U.S. investor-owned electric utilities.

Nevertheless, the electric industry and efficiency and environmental groups say that although the new electric distribution transformer standards set by the DOE on October 12 improve upon an initial proposal issued last year, they fall short of the strong levels the groups had mutually endorsed with ABB, one of the largest transformer manufacturers.

According to the DOE, the initial standards proposed in August 2006 would have saved 238 billion kilowatt-hours of primary energy over 29 years. The higher standards recommended by utility companies (as represented by EEI and the American Public Power Association, Washington, D.C.), the environmental and efficiency groups, and ABB would have saved another 130 billion kilowatt-hours, or 50% more. Last month's final ruling improved on the initial proposal, capturing about two-thirds of the increased savings recommended by the utility, environmental and efficiency groups, and ABB.