Getting the Most From Motors
Originally published January-February 2012
|Higher-efficiency motors include higher slot fills, longer stacks, more copper and lower loss steel. Photo courtesy Nidec Motor Corp.|
Industry in the U.S. runs on motors. And those motors use a lot of electricity.
The industrial sector accounts for roughly one-quarter of the country's electricity consumption. And motor-driven systems use nearly two-thirds of that electricity.
High-efficiency motors could save companies billions of kilowatt-hours—and billions of dollars—annually. That's the impe-tus for federal minimum efficiency standards for motors.
The basis for those standards was established by the Energy Policy Act of 1992 (EPAct92). Those standards, which took effect in 1997, covered most general-use motors from 1 to 200 horsepower (hp). Then, in 2007, the Energy Independence and Security Act (EISA) boosted those standards even higher. See the sidebar on page 19 for details.
The use of more efficient motors and motor systems could save between 62 billion and 104 billion kWh and save up to $5 billion, according to the Consortium for Energy Efficiency.
Making motors more efficient. Motor manufacturers have complied with the standards—first those in EPAct92 and then those in EISA—by using more and better material and tightening tolerances to minimize energy losses.
For EPAct motors, companies used better process controls, took more care in how the coils were wound within the motor and focused on quality control and materials selection. But these steps were not enough to make an EISA motor.
"It certainly was a challenge for manufacturers to produce EISA-compliant motors," said John Malinowski, senior product manager for AC motors at Baldor Electric Co. He offered an example. "A motor has wafer thin pieces of steel, called laminations, which hold the windings. Laminations are placed in a stack to a certain length, which means you need so many pieces in a motor. An EISA motor needs longer laminations, so 20 percent more pieces are needed. At the same time, higher grade steel is thinner than standard grade, so you need about 40 percent more lamination pieces of high-grade steel."
In addition to using better materials, manufacturers also used greater quantities. "More iron and copper in a motor improves its efficiency and life expectancy," said John Caroff, marketing manager for low-voltage motors at Siemens Motors.
By using more copper in the stator windings, the motor runs cooler, said Richard deFay, project manager for sustainable energy at the Copper Development Association. "For every 10 degrees that a motor runs hotter, its operating life is cut in half."
Manufacturers must ensure that tolerances are tightly maintained , incoming materials meet demanding specifications and suppliers are very reliable, added Siemens' Caroff.
While EISA set new minimum efficiency standards, it did not tell manufacturers how to achieve them. "Companies used pretty much the same methods to achieve the required efficiencies," said Baldor's Malinowski. "But manufacturers had ways to squeeze a few watts out here and there. The question was: How much money should be spent on redesign to come up with a different way of getting that higher efficiency."
The new EISA motors, also known as premium-efficiency motors, are rolling off manufacturers' assembly lines. But that does not mean industrial facilities across the country are snapping them up. One reason is the higher cost of more efficient motors.
"In today's economic climate, companies are more likely to repair than replace a failed motor," said the Copper Development Association's deFay.
But whether that decision is repair or replace, it needs to be made well ahead of any failure. That's where a motor management system comes in.
The importance of motor management. Sooner or later, every motor fails. The key is to anticipate that failure, rather than making a repair/replace decision on the spot. By developing a motor management plan before a motor fails, a company can avoid crisis decisions in response to downtime situations.
The first step is a motor survey, which requires a decision on each motor—whether to replace it or rewind it when it fails.
When a motor fails, look at the reason it failed before replacing it, said Baldor's Malinowski. "If it failed because water got inside and shorted the windings, upgrade the mo-tor enclosure. If the motor was overloaded, determine the load and upsize the motor. If the plant survey shows the motor is oversized, install the correct motor rating and energy costs will be reduced."
A motor survey should answer several questions: How many motors are on the system, how often are they used and how well sized are they for the task?
Even a high-efficiency motor won't save energy if it is the wrong motor to begin with. So the survey also should ensure that each motor is the right size for its application and is operated to meet the load required.
EISA vs. EPAct Motors
The Energy Policy Act of 1992 (EPAct92) established minimum efficiency full-load standards for general-purpose motors from 1 horsepower (hp) to 200 hp. The mandated efficiencies ranged from 74 percent to 95.8 percent, depending on the size of the motor, the number of poles and whether the motor is open or closed.
The Energy Independence and Security Act (EISA), enacted in 2007, boosted those standards, mandating efficiencies from 77 percent to 95.8 percent, again depending on motor size, the number of poles and whether the motor is open or closed. In addition, EISA included 1-200 hp motors not covered by EPAct92: U frames, Design C, footless and close-coupled pump motors. The act applies to motors that are manufactured alone or as components of a system.
EISA-compliant motors, known as premium efficiency motors, are up to 3 percentage points more efficient than EPAct-compliant motors, and up to 8 percentage points more efficient than unregulated standard-efficiency motors.
The motors covered by EPAct92, known as energy-efficient motors, are listed in the National Electrical Manufacturers Association's (NEMA) Table 12-11. The motors covered by EISA, known as premium-efficiency motors, are listed in NEMA's Table 12-12.
"In this survey, you're right-sizing," said Baldor's Malinowski. "Bigger isn't necessarily better. It can hurt in terms of the power factor, efficiency and the purchase price." This is also the time to identify those jobs that might benefit from the addition of a variable-speed drive.
But, said Siemens Motors' Caroff, adding a variable-speed drive to a fixed-speed application does not make any sense. "Doing so will just add drive losses to the system," he said.
"No motor needs a variable speed drive," said Malinowski. But if a drive is used to operate a motor at different speeds for certain types of applications, as fan or centrifugal pump speed is changed, it can match the speed of the motor to the requirements, thus saving energy. The use of a drive depends on the system, not the motor, he said.
Elements of the plan. A motor management plan focuses on motors that offer the greatest savings opportunities. It may include:
- Motors that run the most hours or represent critical operation points,
- Larger motors that use the most electricity, and
- Motors that have been repaired mul-tiple times.
In addition, a motor management plan should:
- Establish a logical purchase specification for new motors,
- Determine a cost-effective repair/re-place breakpoint, and
- Define and document appropriate repair standards.
Evaluating the motors used in a plant and deciding how they should be replaced when they fail will ensure that a correct decision is made at the critical time, rather than just selecting any motor to get the equipment moving again.
There are three factors to bear in mind, whether replacing an old, worn-out motor or specifying a motor for a new piece of equipment. First, energy-efficient motors provide savings only when they're running, and the more a motor runs, the more energy and money it saves. Second, maximum savings—and the fastest return on investment—occur in regions of the country where utility rates are highest. Third, any motor has to be properly applied for its intended use.
Taking a systems approach. A high-efficiency motor is only as good as the system in which it operates. The savings realized by a high-efficiency motor system can be up to 10 times the savings from the motor alone. Variable-torque applications, including pumps, fans, blowers, dust collectors and cooling towers, typically offer the greatest returns.
As Baldor's Malinowski pointed out: "It doesn't do much good to put a 95 percent efficient motor on a 50 percent efficient pump."
The question to ask, said Siemens Motors' Caroff, is this: What is the function of this system and can we get more efficient components? "It goes back to what you spend and what is the payback."
Sticker shock. A premium-efficiency motor costs anywhere from 15 to 30 percent more than an EPAct-compliant motor.
"The initial purchase price scares people off," acknowledged Siemens Motors' Caroff.
"In addition to using higher-grade steel, more copper is used in the winding, and as the price of copper has gone up, so has the cost of making a premium-efficiency motor," said Bruce Lung, senior program manager for industrial programs at the Alliance to Save Energy. "If an industrial company is strapped for cash, it may try to nurse its old motors along."
What's in a Name: Trademarking NEMA Premium
When the Energy Independence and Security Act was adopted in 2007, the motors covered by the act's minimum efficiency standards were known as NEMA Premium motors.
Since then, the National Electrical Manufacturers Association has licensed the name. A manufacturer that wants to use NEMA Premium® on a product must demonstrate to NEMA that the product complies with the EISA-mandated efficiencies. In addition, the manufacturer must report its sales to NEMA and submit the product to random testing. The product must meet or exceed the efficiency on its nameplate.
But what industrial companies often don't realize is this: The initial cost of a premium-efficiency motor represents only a tiny fraction—2 percent—of the cost of operating that motor over its lifetime. A full 97 percent of the cost of that motor goes to its lifetime operation.
Short paybacks. In addition to calculating the lifecycle cost of a high-efficiency motor, companies should calculate the payback. Premium-efficiency motors typically have paybacks of two years or less.
Not every motor has a rapid payback, however. Motors that operate only intermittently, for example, accrue savings only when they run. And companies with low utility bills will find that the payback period is stretched out.
In addition, incentives can take a bit of the sting from the more expensive high-efficiency models.
Rebates: Downstream or upstream? Some utilities offer rebates for premium-efficiency motors or what are called super premium motors—those with efficiencies that exceed the EISA standards. In most cases, the rebates are offered directly to customers. But in some cases, those rebates go to motor distributors.
SMMPA. Southern Minnesota Municipal Power Agency, for instance, originally offered rebates to customers of their 18 member utilities for premium-efficiency motors to replace failed ones or build an inventory for future failures. "That rebate was meant to cover a portion of the difference between the cost of a premium-efficiency motor and a standard-efficiency motor," said John O'Neil, manager of energy efficiency & member support programs at the joint action agency.
Currently, SMMPA has a tiered rebate system, with one level for premium-efficiency motors and one for enhanced premium-ef-ficiency motors that exceed NEMA premium levels by at least one percentage point. In addition, higher rebates are available for the replacement of working motors. Rebates for a new motor or the replacement of a failed motor range from $35 for a 1 hp model to $600 for a 200 hp model.
For the replacement of a working motor, SMMPA offers rebates from $100 (1 hp) to $2,400 (200 hp). For inventoried motors, SMMPA offers rebates from $10 (1 hp) to $300 (200 hp). Higher rebates are available for enhanced premium-efficiency motors.
SMMPA received 40 motor rebate applications in 2008. By mid-October of 2011, it had boosted that number to 172, a fourfold increase. Rebate payments in 2008 were $4,890; for the first nine months of 2011, they had reached $46,000. Because of the rebates, the agency estimates that customer savings soared from nearly 75,000 kWh in 2008 to 519,500 kWh as of October 2011.
"Our motor rebate program will change [this] year because of the changes in federal efficiency standards that took effect in 2010," said O'Neil. "Starting in January 2012, we will no long offer rebates for premi-um-efficiency motors for new installations, the replacement of failed motors or for inventoried motors," he said. However, rebates will still be available for premium-efficiency motors that replace working motors and for enhanced premium-efficiency motors that exceed EISA standards by at least 1 percent.
SMMPA is considering incentives for motor distributors and vendors, said Larry Johnston, SMMPA's director of corporate development, agency relations and office of legislative & mregulatory affairs. "We would want to see most of the dollars still making their way to the customer," he said. Such an upstream program might move more high-efficiency motors, said Johnston. "We're interested in helping the businesses that own our members be as efficient and cost-effective as possible. But we also recognize that there may be added benefits to offering an incentive to our trade ally partners."
SRP. Salt River Project in Arizona had a prescriptive rebate program for premium-efficiency motors from 1 hp to 500 hp, said Dan Dreiling, manager of product development. Lastyear, the utility suspended the prescriptive program and it now offers rebates under a custom program for enhanced premium-efficiency motors, on a case by case basis, he said.
SMUD. The Sacramento Municipal Utility District (SMUD) provides incentives to distributors that stock premium-efficiency motors, said Pam Molsick of Energy Solutions, which manages the incentive program for SMUD and other utilities. "We give the incentive to make sure a premium-efficient motor is stocked on the distributor's shelf if a customer needs it right away. Otherwise, they might go down the street and purchase a less efficient EPAct motor."
Until the end of 2011, SMUD offered incentives that ranged from $33 (1 hp) to $1,192 (200 hp). This year, the utility may offer incentives for motors that are more efficient than the premium-efficiency motors, said Molsick.
"The ‘upstream' model for incentives resulted in the sale of 352 high-efficiency motors in 2008—the last good sales year," said Anson Battershell, product services coordinator for SMUD's customer programs and services. "That compares with typical in-house rebated sales of 40 to 70 high-efficiency motors annually."
Educating customers. A number of public power utilities offer seminars to their customers as well as steering them to on-line resources. SRP, for example, sponsors half-day training sessions for customers four times a year. "The feedback from these sessions is very positive," said the utility's Dreiling. "They have helped change customers' mindset about longer term replacement of less efficient motors."
Among the customer representatives attending an SRP's Motor Decisions Matter seminar was Cody Gruwell of the United Dairyman of Arizona. "Two years ago, SRP sent an email to me and our vice president of engineering, telling us about the seminar," he said. "It piqued our interest. We were trying to become more energy efficient, and electricity consumption was a big factor." United Dairyman of Arizona made a commitment to buy only high-efficiency motors in the future. "The rebate made good business sense," said Gruwell.
A Motor Toolkit
For those companies that want to develop a motor management plan or calculate motor paybacks, help is as close as the nearest computer.
The Consortium for Energy Efficiency (CEE) offers a host of helpful information on its website. In addition to such technical resources as its Guidebook for Industrial Efficiency Programs, the consortium manages the Motor Decisions Matter campaign.
"We encourage motor distributors to pass CEE information to customers," said Pam Molsick of Energy Solutions, which manages motor rebate programs for the Sacramento Municipal Utility District and other utilities. "CEE provides an unbiased and scientific look at motor issues." SRP in Phoenix, Ariz., participates in CEE teleconferences and webinars, said the utility's Dan Dreiling. And the city of St. Peter, Minn., used the Motor Decisions Matter site to calculate potential savings from high-efficiency motors.
Motor Decisions Matter is a public awareness program jointly funded by motor manufacturers, the motor repair industry and energy efficiency programs. The aim is to inform the decision-making of industrial facility managers on motor issues by highlighting the financial benefits of premium-efficiency motors, best practice repairs and other proactive motor management strategies. Visit Motor Decisions Matter for more information.
Another valuable resource is Motor Master, which contains a database of more than 27,000 motors. "With Motor Master, the user can make buying decisions based on facts rather than rules of thumb," said Richard deFay of the Copper Development Association. Visit Motor Master for more information.
The Diaryman group uses most of its 700 motors—from one-half hp to 350 hp—to produce nonfat dry milk. An average of 10 million pounds of milk moves through the facility daily. "We're close to the limit of what we can process, so it's critical that we have no downtime.," said Gruwell. That's why UDAZ carries $500,000 worth of inventoried motors and pumps.
The company does not repair any lower-efficiency motor that fails. In the last two years, it has replaced 96 lower efficiency motors with premium-efficiency models.
Southern Minnesota Municipal Power Agency partners with motor distributors and vendors, encouraging them to help educate customers about motor efficiency. "We put together a motor package for customers that included rebate materials and a customized version of Motor Master+ software," said Johnston. "We have developed tailored email marketing messages on motor management and rebate opportunities for specific types of businesses as well as motor distributors."
One of those customers is the water utilities department in St. Peter, Minn. "The city was replacing existing equipment during a water plant upgrade, and we wanted to improve the efficiency and cost-effectiveness of the operation," said Pete Moulton, the wa-ter utilities superintendent. Water and sewage treatment account for one of the highest shares of non-manufacturing electricity use.
The city worked with SMMPA's energy services representative and the equipment vendor. "As a small community, we didn't have in-house expertise," said Moulton.
The city replaced 19 motors ranging in size from 2 to 150 hp that were used in various types of pumps. Some of the replaced motors had failed and others had been refurbished but had maintenance issues, said Moulton. "A couple of the motors dated from the mid-80s and were only 82 percent efficient." Premium-efficiency motors are up to 95 percent efficient.
Most of the motors had a payback period of three to five years, and the city received $8,785 in rebates from its SMMPA member utility.
Does the city have a motor management plan? No, said Moulton, but it is considering developing one. "It makes financial sense."
Higher standards possible. Meanwhile, the U.S. Department of Energy is considering yet another increase in the minimum efficiency standards for motors. The move has been opposed by the American Council for an Energy-Efficient Economy (ACEEE), the National Electrical Manufacturers Association and other groups, which have called instead for an extension of the existing standards to motors not currently covered by EISA.
"Expanding the scope of coverage at the current level offers several advantages," the ACEEE said in October 2010. "This approach would not impose an undue burden on motor manufacturers by requiring new engineering designs and production equipment. Also, the efficiency improvement from bringing uncovered motors up to the current standards level would be much greater than increasing even further the efficiency of a covered motor."
EISA only covers motors from 1 horsepower to 200 horsepower, said Baldor's Malinowski. "Let's raise all motors from 1 horsepower up to 500 horsepower to the premium-efficiency level. That could save five times the energy of DOE's proposal."
Law of diminishing returns. Increasing the minimum efficiency standards from the EISA level would raise the efficiency of covered motors, on average, by 0.7 percent, according to a NEMA study. On the other hand, expanding the scope to include motors not currently covered could increase their efficiency by 2 to 5 percent.
"It would be pretty hard to get more efficiency out of a motor itself, barring some technological breakthrough," said the ASE's Lung. "The most efficient motors are already about 96 percent."
CDA's deFay said the envelope has been pushed so far that the cost of improving efficiency by raising the level yet again is just too high.
The last word. Despite the availability of high-efficiency motors, there are still a lot of inefficient models out there. Many have been stripped down and rewound after failing, buying another decade of operation. The ACEEE estimates that 80 percent of the motors used in the industrial sector today are pre-EPAct models known as standard-efficiency motors.
That means there is still a lot that industrial companies—with the help of their utilities—can do to improve their efficiency and their ability to compete in a global economy.
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