Harmonizing international motor efficiency standards

Gilbert McCoy, EERE Information Center

The International Electrotechnical Commission (IEC) recently passed standard IEC 60034-30 (2008), which defines energy-efficiency classes for single-speed, three-phase, and 50- and 60-hertz (Hz) induction motors. The standard is part of an effort to unify motor testing standards, efficiency requirements and product labeling requirements so that motor purchasers worldwide have the ability to easily recognize premium-efficiency products. Industrial energy managers responsible for offshore facilities and end-users purchasing replacements for failed IEC or metric motors that are imported with equipment packages should be aware of these new efficiency standards.

The new full-load efficiency standards apply to most worldwide industrial continuous-duty motors with the following parameters:

  • Single-speed, three-phase, and 50 Hz and 60 Hz
  • 2, 4, and 6 poles (3,000; 1,500; and 1,000 RPM at 50 Hz)
  • Rated output from 0.75 to 375 (1 to 500 horsepower)
  • Rated voltage up to 1,000 volts
  • Rated on the basis of either duty type S1 (continuous duty) or S3 (intermittent duty) with a rated cyclic duration factor of 80 percent or higher
  • Capable of operating direct online.

The table below shows the new IEC 60034-30 (2008) efficiency classes and comparable efficiency levels.

New International Efficiency (IE) Classes

Efficiency Levels



Standard efficiency

Efficiency levels comparable to the existing EFF2 in Europe


High efficiency

Efficiency levels comparable to the existing EFF1 in Europe and identical to the U.S. EPAct for 60 Hz


Premium efficiency

New efficiency class in Europe and identical to NEMA Premium® in the United States for 60 Hz

The standard also reserves an IE4 class (Super Premium Efficiency) for the future. The following motors are excluded from the new efficiency standard:

  • Motors made solely for inverter operation
  • Motors completely integrated into a machine (pump, fan or compressor) that cannot be tested separately from the machine.

For 60 Hz operation, the IE2 and IE3 minimum full-load efficiency values are virtually identical to the North American National Electrical Manufacturers Association (NEMA) Energy Efficient and Premium Efficiency motor standards, respectively. (NEMA does specify different full-load efficiency values for motors with totally enclosed fan-cooled [TEFC] and open drip-proof enclosures.) The IEC minimum full-load efficiency standards are higher for 60 Hz motors than for 50 Hz motors. This is because as long as the motor torque is constant, I2R or winding resistance losses are the same at 50 Hz and 60 Hz. The motor output power, however, increases linearly with speed, increasing by 20 percent when the frequency is increased from 50 Hz to 60 Hz. In general, the 60 Hz efficiency is about 2.5 percent to 0.5 percent greater than the 50 Hz values. The efficiency gain is greater for smaller motor power ratings.

This photo shows a motor in an industrial plant environment which is being measured by a person holding a square testing device with a screen. The testing device is connected to the motor by a cable.
The new IEC 60034-30 motor efficiency standard could have major energy-saving impact for industrial motors worldwide.

Unifying Worldwide Efficiency Classifications
To show compliance with these new efficiency standards, motors must be tested in accordance with the newly adopted IEC 60034-2-1 testing protocol. This procedure provides test results that are largely compatible with those obtained by the North American IEEE 112B and CSA 390 test methods.
The new standard also requires that the motor efficiency class and nominal motor efficiency be labeled on the motor nameplate and given in product literature and motor catalogs in the following format: IE3 94.5%.

New Minimum Energy Performance Standards
While the IEC sets guidelines for motor testing and efficiency classes, the organization does not regulate efficiency. With the new efficiency standards in place, the European Commission Eco-design Regulatory Committee recommended in March 2009 that electric motors with an output power of 0.75 to 375 kilowatts (kW) equal or exceed new mandatory Minimum Energy Performance Standards (MEPS). The MEPS, expected to be adopted in June 2009, are set at the following levels:

  • IE2 by June 16, 2011
  • IE3 by January 1, 2015 (for motors >=7.5 kW, or IE2 with an adjustable-speed drive)
  • IE3 for all motors by January 1, 2017 (or IE2 with an adjustable speed drive).

The new MEPS will supersede the existing voluntary 1999 European Committee of Manufacturers of Electrical Machines and Power Electronics EFF1, EFF2, and EFF3 efficiency standards.

Adoption of the MEPS by the European Commission will put them on a path similar to that taken by the United States in the Energy Independence and Security Act (EISA) of 2007 (PDF 151 KB). Download Adobe Reader. This act increases the U.S. MEPS for 1- to 200-horsepower, 1,200, 1,800 and 3,600 RPM general-purpose motors from the Energy Policy Act of 1992 Energy Efficient (IE2 equivalent) levels to NEMA Premium Efficiency (IE3) levels by December 2010. EISA also establishes an Energy Efficient (IE2) level for motors with output power ratings of 201 to 500 hp.

For additional information, you can purchase the new IEC standard on motor efficiency classes, or download the Motor MEPS Guide (PDF 4.2 MB). Download Adobe Reader. Also, watch for the IEC 60034-31 Guide for the Selection and Application of Energy-Efficient Motors Including Variable Speed Applications, which will be available soon.

In addition, visit the U.S. Department of Energy Industrial Technologies Program software tools Web site to learn about and download the MotorMaster+ International software tool.
Read More Energy Matters Articles on These Topics

This article was written for the U.S. Department of Energy’s Industrial Technologies Program and appeared in the Summer 2009 issue of the DOE’s Energy Matters newsletter. For more information, visit http://www1.eere.energy.gov/industry/.

Subscribe to Reliable Plant

About the Author