According to the U.S. Department of Energy (DOE), electric-motor-driven equipment uses 25 percent of all of the electricity consumed in the United States. With premium-efficiency motors with adjustable-speed drives, significant electricity savings are possible.

HISTORY OF PREMIUM EFFICIENCY IN THE UNITED STATES

During the early 1980s, several manufacturers introduced “premium”-efficiency motors, which used better lamination material, more active material (laminations and copper), and lower-loss cooling fans. But there were no guidelines as to the efficiency a motor needed to produce to be considered “high-efficiency.”

The National Electrical Manufacturers Association (NEMA) first made a distinction between standard and energy-efficient motors with the 1990 revision of its MG 1-1987 standard, which would become the standard for the Energy Policy Act of 1992 (EPAct). In October 1997, the EPAct took effect, mandating minimum energy-performance standards (MEPS) for 1- to 200-hp (0.75 to 150 kw) two-, four-, and six-pole general-purpose totally enclosed fan-cooled (TEFC) and open-drip-proof (ODP) foot-mounted motors. This required that any EPAct motor manufactured for sale in the United States comply with minimum nominal-efficiency, testing, and labeling standards. The EPAct does not cover “special-purpose” motors, such as footless motors with C-faces, or close-coupled pump mountings.

The Consortium for Energy Efficiency (CEE) established “premium”-efficiency guidelines that were used by many utilities for rebate programs in 1996. By August 2001, NEMA and CEE harmonized their efficiency standards, establishing NEMA Premium efficiency standards for 1- to 500-hp (0.75 to 370 kw) two-, four-, and six-pole low- and medium-voltage TEFC and ODP motors. The NEMA Premium standard first defined in NEMA MG 1-1998, Revision 2, does not differentiate between mounting configurations, and all types of motors are covered.

EPAct 2005 mandates that the U.S. government purchase NEMA Premium motors per the Federal Energy Management Program (FEMP) (www1.eere.energy.gov/femp/procurement).

EFFICIENCY OUTSIDE OF THE UNITED STATES

The European Union (EU) and European Committee of Manufacturers of Electrical Machines and Power Electronics (CEMEP) have developed a voluntary efficiency-classification scheme for motors in the 1.1-to-75-kw range. “Eff1” designates the highest-efficiency motors, comparable to U.S. EPAct motors, while “Eff2” designates standard-efficiency motors, and “Eff3” designates motors the EU is encouraging manufacturers to discontinue. Discussions to set MEPS, as the United States has done with the EPAct, are under way.

Table 1. IEC 60034-30 efficiency levels.

In 2005, Paulo Bertoldi of the European Commission Joint Research Centre initiated Standards for Energy Efficiency of Electric Motor Systems (SEEEM) with the goal of establishing global performance standards and testing methodology. As of 2008, motor test standards had been harmonized between Institute of Electrical and Electronics Engineers (IEEE) 112b, Canadian Standards Association (CSA) 390, and International Electrotechnical Commission (IEC) 60034-2-1. These new efficiency designations are scheduled to replace the CEMEP Eff markings in April 2009. Efficiency standards still differ between NEMA and IEC, but work continues. IEC 60034-30 specifies new efficiency levels for motors (Table 1).

Because of the design of IEC motors, manufacturers have difficulty reaching efficiencies higher than IE2 without significant electrical redesign and/or the use of larger frames. IE3 is not supported by leading European manufacturers because of the high costs of retooling. CEMEP agrees with the EU measure to adopt IE2 as an MEPS in 2011. A proposal to increase efficiency using IE2 motors with adjustable-speed drives is being studied. IE3 would become a “self-regulation of the class IE3, which means the industry commits itself on a voluntary basis to develop, launch, and monitor IE3 motors on the market.”¹