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Buy A New Motor or Repair the Old One? (Part 2)

July 22nd, 2010

How Best to Comply with EISA if You Need to Fix or Replace a Commercial Motor

By David Brender, Copper Development Association (CDA) National Program Manager

Any new motor manufactured or sold after December 10, 2010 must meet certain energy efficiency standards, as stated in the Energy Independence and Security Act of 2007. David Brender, of the Copper Development Association, has some tips on how to comply with the new law.   

There are a number of reasons you’ll want to replace a motor, primarily because an existing motor has failed, or it may not have failed, but it’s inefficient. The electricity the motor uses is about 98 percent of the cost of owning the motor. The purchase price is almost insignificant. In fact, with load cycles typical of an industrial or commercial application, the first cost of a motor may represent only one or two percent of the full cost of ownership. Most people don’t consider that – they just want the cheapest one. But that’s not the way to look at it.

Ask yourself how much money you might save by using a new, more efficient motor. You can often pay back the initial price in less than a year because of lower operating costs. You’ll have a faster payback if you’re in a higher electric cost operating area versus a lower cost one or the hours of operation are high. Cost is an important consideration, but the purchase decision needs to take operating costs into account. 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 on a first-cost basis to repair the older motor. But you get back the possibly lower efficiency motor you may have begun with or less. You can’t improve the original efficiency.

Put another way, if you rewind an old motor, the initial cost will be about 70-80 percent of the price of a new one. You save money initially, but not necessarily in operating costs if it was an inefficient model to begin with. And the cost of operating a motor is generally far greater than the purchase price. Therefore, it would behoove the user to look into replacing rather than rewinding the motor.

If you’d like to know whether  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 10,000 motors.

Then you can calculate how much you’d save if you rewound your motor or replaced it. The software takes into account all sorts of variables from load factor and motor efficiency to purchase price and energy costs.

You also can get a free MotorSlide Calculator ™. This slide rule device will help you 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.

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