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MotorsEnergy-Smart InvestmentPremium Efficiency Motors As the benefits and savings of premium efficiency motors become more commonly recognized, so to do sales. NEMA estimates that between 2001 and 2002, total net units shipped increased 30 percent. Shipments rose another 14 percent between 2002 and 2003. To calculate cost savings from a premium efficiency motor, use this calculation:
To demonstrate how a slight improvement in efficiency can result in significant cost savings, consider a hypothetical premium efficiency motor with the following specifications:
Under these conditions, a four-percent increase in motor efficiency will save an estimated $797 annually. Assuming an operating lifespan of 10 to 15 years, our hypothetical motor could save upwards of $10,000 over the course of its useful life. Even greater savings can be expected from efficient motors with higher horsepower and longer operating hours:
Estimated annual savings in grey boxes. Assumptions: .75 load factor, 6,552 operating hours and a four-percent increase in motor efficiency.
Estimated annual savings in grey boxes. Assumptions: .75 load factor, 50 hp and a four-percent increase in motor efficiency.
The best way to decide between motor repair and motor replacement is to first calculate potential energy savings and then calculate simple payback (this calculation is also useful comparing standard efficiency motors to premium efficiency motors). Use the formula above to calculate expected energy savings, then add this calculation: Simple payback = Premium price ÷ Annual savings
Recommendations based on Consortium for Energy Efficiency's brochure Efficient Motors: Selection and Application Considerations. Variable speed drives A VSD typically comes as a stand-alone control box that is capable of precisely tailoring motor speed to load demand. The process is both straightforward and elegant: rather than mechanically modifying the motors they control, the VSD precisely regulates motor speed by moderating the flow of electricity to attached motors. VSDs run very efficiently; is not unusual for the VSD itself to be more than 94 percent efficient right down to 50 percent load or less. VSDs also offer the added benefits of helping to cut down on motor noise, improving production efficiency and eliminating the "voltage sags" (often evident from temporarily dimmed lights) common to motor startup. Prices for VSDs vary greatly, although as a general rule a basic VSD will cost roughly the same as the motor it drives. In many cases, initial capital costs can be offset by rebates and other incentive programs sponsored by local utility providers. Specifying Premium Efficiency Motor Purchases
NEMA Premium Efficiency Motors
Resources See Flex Your Power product guide on motors. The National Electric Manufacturers Association (NEMA) website contains information on the NEMA Premium® energy efficiency motors program, including product specifications and a list of participating partners. The Consortium for Energy Efficiency (CEE) website on Motors and Motor Systems includes a Motor System Tool Kit, efficiency specifications, resource links and information on the Motor Decisions Matter campaign. Efficient Motors: Selection and Application Considerations. A brochure developed by CEE and the U.S. Department of Energy's Motor Challenge Program. Boston, MA: 1999. U.S. Department of Energy (DOE) free software MotorMaster+ is an energy-efficient motor selection and management tool, including a catalog of over 20,000 AC motors. This tool features motor inventory management tools, maintenance log tracking, efficiency analysis, savings evaluation, energy accounting, and environmental reporting capabilities. U.S. DOE free softwarePumping System Assessment Tool (PSAT) helps industrial users assess the efficiency of pumping system operations. PSAT uses achievable pump performance data from Hydraulic Institute standards and motor performance data from the MotorMaster+ database to calculate potential energy and associated cost savings. Electrical Apparatus Service Association (EASA), Inc. is an international trade organization of over 2,150 electromechanical sales and service firms in 50 countries. The EASA website contains downloadable, in-depth guidelines to improve motor efficiency, repair worn or malfunctioning motors, and to help owners decide whether to replace or repair motor systems. |