Making Workhorses Efficient

Motors consume about 50 percent of electricity in the United States and more than 67 percent of electricity used by industry, states R. Neal Elliott, industry program director with the Washington, D.C.-based American Council for an Energy-Efficient Economy (ACEEE,

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With these industrial workhorses having an energy hunger that huge, it makes sense for companies to investigate National Electrical Manufacturers Association (NEMA, Premium energy-efficiency motors. They’re available in most any configuration, any kind of enclosure or special mountings, says John Malinowski. Among others, those include wash-down duty for food
processing, C-face, D-flange and explosion-proof, explains this product manager for AC/DC motors at industrial-motor manufacturer Baldor Electric Co. (, Ft. Smith, Ark.

“NEMA Premium defines efficiency of motors, not mechanical attributes,” Malinowski states. Those efficiency levels appear in tables 12-12 and 12-13 of NEMA Standard Publication MG 1- 2003. Those tables contain nominal efficiencies that low-voltage and medium-voltage motors, from one horsepower (HP) to 500 HP, must have to be labeled NEMA Premium.

More attention on motors’ lifecycle costs continues to drive increased interest in these higher-efficiency motors—and for good reason. Malinowski estimates initial purchase price equals about 2 percent of a typical general-purpose motor’s lifetime costs. But energy costs exceed more than 97 percent of that motor’s total lifecycle costs, he says. Even so, it’s not just operating costs of electricity that motor purchasers should consider, he emphasizes, “but getting a motor that will last a long time before failure.”

When failure occurs, decision time arrives. But before making choices, end-users should know about potential energy savings through motor management, says Ted Jones, senior program manager with Boston-based Consortium for Energy Efficiency Inc. (CEE, To him, that means basing repair/replace decisions on lifecycle costs. “It’s a recognition that those decisions have long-term financial implications.” Malinowski adds that industry may be replacing more motors now than repairing them.

Understanding costs

Something bothers Jones, however. While NEMA Premium motors are available, end-users may not necessarily be aware that these more efficient alternatives exist. He says the condition exists because purchasing agents or maintenance staff often make buying decisions. “The pressure is to make the lowest-cost choice,” states Jones, who also works with CEE’s Motor Decisions Matter ( campaign, which attempts to raise end-users’ awareness.

As the old saw goes, though, you get what you pay for. However, if end-users are willing to pay more, they may get even higher efficiency with copper-rotor motors than with NEMA Premiums. For one to 200 HP industrial motors, copper-rotor ones look like the next technology to lower motor operating costs. At least that’s the opinion of Nicole Kaufman Dyess and Emmanuel Agamloh, both of Advanced Energy (, Raleigh, N.C. They presented their view in the 2007 ACEEE Summer Study on Energy Efficiency in Industry, through “Copper Rotor Motors: A Step toward Economical Super-Premium Efficiency Motors?”

Early adopters of these motors are those who understand lifecycle costs and who are really committed to make a change, Malinowski believes. Still, “because people are hedging [with purchases of Premium motors] because of their high cost, the copper-rotor motor might also be resisted,” he speculates.

Potential resistance didn’t appear to deter Bruschal, Germany-headquartered SEW-Eurodrive ( from producing its copper-rotor motors. Nor did it dissuade Alpharetta,
Ga.-based Siemens Energy & Automation ( from offering small copper-rotor motors. Of theirs, Siemens indicates they cost a few percent more than aluminum-rotor Premium motors, but may have up to 10 percent higher efficiency.

Regardless of type of higher-efficiency motors, it appears they’re finding more use. To Malinowksi, it’s obvious why. “People are becoming more mindful of the cost of operating a motor.” “People are becoming more mindful of the cost of operating a motor.”

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