If You Plan to Buy an Electric Motor in 2010 - Read This

May 3, 2010


The U.S. Department of Energy has New Energy Efficiency Requirements for Commercial-Size Motors

New York, NY— A new federal regulation designed to improve energy efficiency in industry goes into effect this year. The regulation requires certain efficiency standards in new motors of a commercial size. This new law not only will reduce wasteful energy use, it will be beneficial to the copper industry, according to the Copper Development Association (CDA).

The Energy Independence and Security Act of 2007 (EISA) aims to slow down and eventually reduce America's energy consumption. It's important to understand EISA if you're a facility manager, plant electrician or anyone who plans to purchase a commercial-size electric motor this year. EISA expands on previous energy policy acts, expands the range of motors covered and the mandated efficiency of some of them.

Any new motor manufactured and sold after Dec. 10, 2010 has to be of a certain minimum efficiency standard. Although this is a small provision in the Act's 822 pages, the change could bring about a very large reduction in wasteful energy use, says Richard deFay, CDA project manager and electrical applications specialist.

"You can save your organization money and boost efficiency many times over by factoring life cycle cost in addition to the initial cost of motors you're considering," he says.

Electric motors account for nearly 50 percent of total U.S. energy use, and two-thirds of energy use in industrial settings. The savings in kilowatt-hours and in dollars for both individual users and the U.S. as a whole could be great.

"In terms of the copper industry, that's a good thing because higher efficiency motors need a lot more copper," says David Brender, the CDA's national program manager. "It's also good for users because the more efficient motors will save them money in the long run."

Users would be smart to move forward on compliance because they can pay back the initial investment quickly and the product is on the market now, Brender says. The NEMA (National Electrical Manufacturer's Association) Premium is the designation now used to identify high efficiency motors. For consumers looking to buy a new motor, look for the NEMA Premium label.

Why Replace an Existing Motor?

There are a number of reasons:

  • An existing motor has failed or it's inefficient.
  • A new process requires a different piece of equipment.

If an existing motor fails, the owner has two choices - he can buy a brand new motor or he can rewind and repair the older motor. It's typically cheaper to repair the older motor. But you get back exactly what you got to begin with or less and you can't improve the efficiency.

If you rewind an old motor, that's about 70-80 percent of the cost of a new one. You save money initially, but not in operating costs. And the cost of operating a motor is generally greater than the purchase price of the motor. Therefore, it would behoove the user to look into replacing rather than rewinding the motor.

Installing more efficient motors almost always saves enough money to pay off the new motor quickly. There are exceptions: motors that operate only intermittently (low duty cycle) will save less since they only accrue savings while running. Low utility rates (the national industrial average is around $0.07/kWh) will also stretch out the pay-back time. On the other hand, many utilities and some jurisdictions offer rebates or credits to companies that install more efficient motors, a practice that reduces up-front cost and shortens pay-back times considerably.

Look at some numbers. The table below lists payback periods for NEMA Premium motors compared with rebuilding existing standard-efficiency motors. Analyses are based on MotorMaster+ using data supplied by motor manufacturers. Motors are assumed to operate at 75% load for 8,000 h/y. The utility rate used is $0.067/kWh.

Annual Savings and Payback Periods for New NEMA Premium Motors vs. Rewinding a Standard-Efficiency Motor
HP Annual Savings Payback, years
1 $54 0. 81
5 $148 0.75
10 $242 1.01
20 $374 1.22
25 $445 1.56
50 $645 2.21
100 $1281 2.38
200 $2339 2.45
500 $3551 4.66

For all but large motors (which tend to be highly efficient), the replace vs. rewind decision is obvious. Think of a one-year payback as a 100% return on investment and upgrading to a NEMA Premium motor becomes an obvious choice.

For more information on how to cost-effectively replace or repair a motor, check out the software MotorMaster+ available at no charge through the U.S. Department of Energy website. It's a respected, non-biased source for motor data. With MotorMaster+, you can find motor efficiency, list prices, payback analysis and return on investment. MotorMaster+ has data on more than 25,000 motors.

The free MotorSlide Calculator™, a slide rule device, can help calculate approximate annual savings in choosing a NEMA Premium electric motor (or any level of efficiency) over a lower efficiency motor. Click here for more information on how to get it.