Understand the New Motor Standards

May 27, 2010
Regulations will require higher energy efficiency for many AC motors.

Motors manufactured after December 19, 2010, for sale in the United States are affected by the Energy Independence and Security Act of 2007 (EISA). EISA was passed by Congress and signed into law on December 19, 2007. EISA builds upon the Energy Policy Act of 1992 (EPAct) by raising mandated efficiency standards for general-purpose three-phase 1–500-hp. AC industrial motors.

Standards for each general-purpose rating (subtype I) from 1 to 200 hp. previously covered by EPAct increase to the nominal full-load efficiency level for "NEMA Premium" given in Table 12-12 in NEMA "Motors and Generators," Revision 1 (MG 1 - 2009) — see Table 1. (For more information on the standards, go to www.nema.org/stds/mg1.cfm.) These are 230/460-V., 60-Hz., Design B, 2-, 4- or 6-pole AC induction motors.

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General-purpose electric motors (subtype II) previously not covered by EPAct must meet efficiencies defined in Table 12-11 in MG 1 (Table 2). These motors incorporate design elements of a subtype-I general-purpose unit but are configured as one of the following:
• U-frame motor;
• Design C motor;
• close-coupled pump motor;
• C-face or D-flange footless motor;
• vertical solid-shaft normal thrust motor (as tested in a horizontal configuration);
• an eight-pole motor (900 rpm);
• a poly-phase motor of not more than 600 V. (other than 230 or 460 V.); and
• 201–500-hp. motors previously not covered by EPAct.
EISA-mandated efficiency levels for subtype-I motors fall within efficiencies of existing general-purpose 1–200-hp. NEMA Premium efficient motors, such as Baldor's Super-E.

Motor Subtype I Efficiencies
Table 1. All such motors must meet NEMA Premium efficiency as specified in NEMA MG1, Table 12-12. Source: NEMA MG 1-2009. Used with permission.

Manufacturers of some designs of subtype-II 1–200-hp. and general-purpose 201–500-hp. motors may have to raise their efficiency; however, many designs may already comply. NEMA Premium efficient motors meet or exceed EISA requirements for either of these motor types.

EISA doesn't apply to fractional-hp. and 48- or 56-frame motors. It only covers 1–500-hp. motors with three-digit frame NEMA numbers (143T and up) or equivalent IEC designations of frames 90 and larger (excluding IEC100).

Not every three-phase 1–500-hp. motor configuration falls under EISA — but almost all motors except some special OEM designs with proprietary mounting configurations do. The following configurations are exempt from EISA compliance:
• single-phase motors;
• DC motors;
• totally enclosed non-ventilated and totally enclosed air-over enclosures;
• Design D with high slip;
• integral with gearing or brake where the motor can't be used separately;
• inverter duty motors with windings optimized for adjustable-speed-drive use that can't be line-started;
• Design D high-slip motors;
• customized OEM mounting;
• intermittent duty motors; and
• submersible motors.

EISA requires any custom motors included in OEM equipment that falls within the guidelines of the act to comply with efficiency levels for that type of motor. Each OEM should prepare for the changes well before December and develop designs immediately, particularly when UL or CSA approvals are required.

EISA makes no distinction for duty cycle rating. It's necessary to look at the EPAct definition of "electric motors" and "general purpose" to determine if a particular design falls under the requirements.

EISA also doesn't distinguish between stock and custom motors. The determining factor is whether a particular unit meets the law's definition of "electric motor."

EISA applies to motors imported into the U.S., including ones that are components of another piece of equipment. It doesn't apply to motors exported from the U.S., including ones mounted on equipment. These motors or their boxes must be specifically marked "Intended for Export." (Other countries are enacting their own minimum efficiency performance requirements for motors. Canada's version of EISA takes effect on January 1, 2011. Mexico's version likely will resemble the U.S. EISA, except it only will apply to stock motors sold through distribution and available to the public, not custom motors or motors orders by OEMs and users.)

EISA doesn't require replacement of motors in use. The law doesn't affect the repair of motors already in service. It also doesn't impact inventories — motors on hand as of December 19, 2010, can be sold or used as before the law.

Motor Subtype II Efficiencies
Table 2. These motors must achieve efficiencies as specified in NEMA MG1, Table 12-11. Source: NEMA MG 1-2009. Used with permission.

Efficiency Determination
Full-load nominal efficiency must be established using the same test methods as stipulated in EPAct, namely those specified in NEMA MG1-2006 and IEEE Standard 112, Test Method B, or CSA 390. Manufacturers like Baldor already determine such efficiencies in accordance with these standards.

Like EPAct, EISA requires a motor's nameplate to state the nominal full-load efficiency. All motors produced today should include this information for EPAct.

A revised industry standard, IEEE 841-2009, "IEEE Standard for Petroleum and Chemical Industry — Premium Efficiency, Severe-Duty, Totally Enclosed Fan-Cooled (TEFC) Squirrel Cage Induction Motors — Up to and Including 370 kW (500 hp.)," was recently released. It raises the efficiency level of 841 motors to NEMA Premium levels, mandating these motors' compliance with EISA.

The U.S. continues to lead the world in use of premium efficiency motors. The European Union will require premium efficiency motors in 2017.

John Malinowski is senior product manager for AC motors at Baldor Electric Co., Fort Smith, Ark. E-mail him at [email protected]

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