With the current economic climate putting a squeeze on capital budgets, now is the time to improve the efficiency and productivity of existing motor systems such as pumps, fans and air compressors.
According to a U.S. Department of Energy (DOE) study, the U.S. chemical industry consumed approximately 6.3 quads1 of energy in 2001. This amount represents approximately 6 percent of domestic energy use and about 19 percent of all U.S. manufacturing energy use for that year. DOE also estimates that greater attention to motor system management could reduce chemical plant energy consumption by as much as 18 percent.
Defining motor management
Motor management entails a variety of practices that capitalize on the benefits of premium-efficiency motors (lower operating costs and improved reliability) and best motor repair practices (maintain efficiency, optimal availability). It includes:
A decision-making protocol based on life-cycle costing for making purchase and repair/replace decisions.
Procedures to inventory and categorize motors.
Practical advice on making sure the optimal motor for critical applications will be available when needed.
Guidelines to ensure quality repair services.
Motor Decisions Matter, a national educational campaign, is working to spread the word about the benefits of motor management and premium-efficiency motors and to empower companies to adopt these practices. Campaign sponsors include motor manufacturers, utilities, energy-efficiency organizations, trade associations and governmentagencies. (For more information, see www.motorsmatter.org.)
Figure 1. Motor Systems Energy Use
Source: Xenergy study, 2001
Motor management importance
Over a motor's lifetime, its electric bill accounts for over 97 percent of its total cost. Less than 3 percent of the lifetime cost goes toward its purchase, installation and repair. For example, consider a 75-horsepower (hp) motor running at full load for 6,000 hours per year. A typical purchase price would be approximately $4,000. Over its 10-year life, however, that same motor would cost $220,000 to run (based on $0.075 per kilowatt-hour [kWh]).
It becomes apparent that small increases in efficiency translate into big savings. In this example, a one percent increase in motor efficiency translates into $2,800 in energy savings over that time ," nearly the cost of the motor.
Implementation of a motor management plan often improves productivity. The first step to plan implementation is to gain an understanding of your motor fleet and to catalog it. One of the benefits of this review process is that it quickly identifies applications with older inefficient motors and improperly sized motors that should be replaced based on their economic performance. The economic analysis also will indicate whether these motors should be replaced immediately or upon failure. Plants that have large motors and motors running critical processes stand to gain the most from the review in terms of economic return and reduced downtime.
Motor management also could reduce downtime attributed to motor failure. Premium-efficiency motors typically are constructed with superior materials and have more copper, tighter tolerances and longer warranties.
Figure 2. Motor System Energy Use within SIC 28
Source: Xenergy study, 2001
The management plan
Identification of appropriate applications for premium-efficiency motors is an important component of every motor management plan. An understanding of what motor efficiency levels are available and how to specify them is equally important.
Working closely with the National Electrical Manufacturers Association (NEMA), also a campaign sponsor, the Consortium for Energy Efficiency established a premium-efficiency specification and brand, called NEMA Premium, which motor manufacturers, distributors, repair shops, energy efficiency organizations and motor incentive program administrators now embrace. (For more information, see www.nema.org/premiummotors.)
Motor repair quality also is an important consideration when analyzing motor repair/replacement decisions. Proper evaluation requires a comparison of total repair costs (repair plus energy and life-cycle operating costs) with total replacement costs with a NEMA Premium motor (purchase plus energy and life-cycle costing) before you are able to determine which option will achieve the greatest economic return.
When the repair option is appropriate, you must exercise care to ensure all repairs do not deviate or deviate very little from the motor's original energy specifications because improperly performed repairs can decrease motor efficiency by as much as 2 percent. For more information about what constitutes quality repair and how to specify it for your motors, see the Electrical Apparatus Service Association (EASA) guidelines on best practice repair (www.easa.com, under Industry Resources).
Finally, motor management is about planning. Too often, repair/replace decisions are based on motor availability or short-term economics ," not long-range planning. Motor management provides the financial analysis tools you need to make good motor decisions and offers direction for developing cost-effective, pro-active purchasing and repair/replace policies. The Motor Decisions Matter Web site (www. motors matter.org) offers a motor planning toolkit to help you get started on development of your facility's plan.