Premium-efficiency motors: soon they'll be law.

In a little more than a year from now, most of your new motors must meet new efficiency levels mandated by federal legislation.On October 24 of next year and thereafter, most new motors manufactured must be of "energy-efficient" design. The Energy Policy Act of 1992 (EPACT) stipulates that most standard-efficiency motors will no longer be manufactured after that date. Subsequently, only premium-efficiency

In a little more than a year from now, most of your new motors must meet new efficiency levels mandated by federal legislation.

On October 24 of next year and thereafter, most new motors manufactured must be of "energy-efficient" design. The Energy Policy Act of 1992 (EPACT) stipulates that most standard-efficiency motors will no longer be manufactured after that date. Subsequently, only premium-efficiency (PE) motors will be manufactured.

The term "premium-efficiency" appears to be replacing the commonly used terms "energy-efficient" and "high-efficiency" when referring to motors that have a higher efficiency than standard-efficiency motors. The National Electrical Manufacturers Association (NEMA) uses the term "energy-efficient."

Which motors are affected?

The law applies to any general-purpose, T-frame, single-speed, foot-mounted, polyphase induction motor of Design A and B configuration that is continuous rated and operating at 230/460V, 60 Hz, as defined in NEMA Standard MG 1-1987, Motors and Generators. Motors affected are rated from 1 to 200 hp, drip-proof, and totally enclosed.

Each part of the above description is important. If the motor doesn't fit the description, then EPACT does not apply. For example, the law doesn't apply to 120V, 200V, 208V, Design C, or DC motors. Also note that wound-rotor and synchronous motors are not affected. However, EPACT does apply to single-speed motors and/or those that are foot-mounted; this covers more than 80% of the motors used. Furthermore, affected motors are those that are "as defined in NEMA Standard MG 1-1987."

The Table, on page 36, is derived from Table 12-10, Full-Load Efficiencies of Energy-Efficient Motors, in Part 12 of MG 11993. This table shows data only for 1800-rpm motors. The complete table, which is a revision of an earlier Table 12-6C, is included in MG 1-1993 and includes data for 2-, 4-, 6-, and 8-pole motors. Also, in accordance with NEMA standards, the table covers "Open Motors" and "Enclosed Motors." The values given are "nominal full-load efficiencies," which are obtained from the average efficiency of a population of motors of duplicate design as determined by NEMA Standard MG 1-1987.

Table 12-10 now also lists efficiency values for motors up to 500 hp (although EPACT applies only to motors up to 200hp) as well as minimum efficiency values.

The law clearly exempts definite-purpose and special-purpose motors assumedly because their characteristics and applications are inappropriate for energy conservation. It also provides for special petitions for exemptions where the application will not result in significant energy savings, as where the motor would be used infrequently or in other inappropriate applications.

It appears that where a motor is clearly built for a special application, it would qualify for exemption from the law. On the other hand, a motor built to "standard specifications" but applied to a special application, such as a fire-pump motor that rarely runs, may not be exempt.

Testing and labeling

Testing of PE motors will be in accordance with NEMA standards and IEEE/ANSI 112-1991, IEEE Standard Test Procedure For Polyphase Induction Motors and Generators, Test Method B. It appears that manufacturers will test and label motors themselves for the time being. However, discussions are under way that may lead to "certification" of each manufacturer's testing facility. How this will be done is unclear. Possibly, an enforcement agency will be created.

Another possibility is the appointment of an independent testing laboratory. One possible "third-party" testing agency mentioned is the National Voluntary Laboratory Accreditation Program (NVLAP), which is a subdivision of the National Institute of Standards and Technology (NIST).

It's not clear who or if any third-party testing will be implemented. Possibly, independent motor consultants, experts, or associations will eventually be the ones to do the testing, if enough can be found.

Imported motors present a problem. Manufacturers of foreign-built motors tend to place their own efficiency values on the motors, which is confusing to end users. These motors should be subject to the same testing and labeling requirements as all U.S.built motors to protect end users. At this time, however, enforcement or verification of foreign-built motors are uncertain.

Labeling of the new motors is mandated. EPACT calls for the nameplate and pertinent literature to prominently show the motor's efficiency. This value must be the "nominal efficiency," and be identified as such. The "guaranteed minimum" efficiency of the motor may be placed on the motor nameplate if desired.

Canada has already started

Canada implemented a motor efficiency act in January 1996. Their law is based on the U.S. law and seems to be working well. It appears that the Canadian Standards Association (CSA) will provide for efficiency testing of motors, but this too has not been definitely established. British Columbia actually initiated an energy efficiency law effective January 1995.

A new NEMA Design E motor may be available by the time of this writing and will have the highest efficiency. However, this type of motor has a few somewhat undesirable characteristics, such as very high starting currents and inadequate torque characteristics. The latter may make the Design E motor unable to directly replace a Design B motor. As a result, care must be taken when applying the Design E motor.

Other new motor designs are on the way. One type is designed to operate with adjustable frequency drives (AFDs) and is already available. This motor operates cooler than one "unmatched" to the AFD. New insulations should help alleviate problems attributed to AFDs and other sources of harmonics and poor power quality.

Other concerns

Consortiums for energy efficiency have been formed and received grants to promote energy savings. One is the "Motor Challenge" operation, which consists of manufacturers, industrials, distributors, and service firms whose function is to inform, educate, and train users of the benefits of energy-efficient motors and systems. If the Department of Energy (DOE) is funded adequately under the pending 1996 budget, additional agencies will be funded to save energy.

Rebates are on their way out. After all, if an energy-efficient motor is the law, why offer a rebate? Some utilities will offer rebates for very high efficiency motors and installations, and certain programs will be retained to illustrate motor efficiency, proper motor selection, circuit design, and motor installation.

A major concern is the effect on OEMs who buy thousands of motors. They will, no doubt, have to adjust to different motor characteristics such as motor torques, starting currents, slightly higher motor speeds, and probably higher prices.

Other concerns include the many technical and application characteristics of PE motors. As an example, inrush currents of some PE motors are significantly higher than standard motors; thus a higher protective relay setting may be required. Similar concerns are in order for starters and controls, overloads, underloads, unusual running modes, torque requirements, etc. The National Electric Code (NEC) addresses some of these in its 1996 edition.

Also, a costly PE motor should be checked for proper installation. If mounting bolts are loose or alignment with the load is incorrect, excessive vibration could nullify any efficiency gained.


These are the salient points as published, and some of the relevant effects of EPACT. There are many others. A reliable source says that in 1993, 16% of all 1-to-200 hp induction motor sales were PE motors. Ten years ago, this figure was about 5 %. But by the year 2000, it's assumed that most new motor sales, particularly of the common integral induction motor type, will be of PE design. The dollar value is estimated to be approximately $800 million.

TAGS: Design
Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.