Consulting-Specifying Engineer - December 2008 - (Page 58)

Equipment Lifecycles Table 1 20 hp 4-pole operating costs Efficiency Electrical cost per year Annual savings DOE average efficiency motor 88.6% $14,752 0 EPAct highefficiency motor 91.7% $14,253 $499 NEMA Premium efficient motor 93.0% $14,054 $698 x 20 years changed, the load changes by the cube of the speed change. So, a fan operated at half speed only requires 12.5% of the energy to operate it, rather than run at full speed with a damper. The return on capital for upgrading to an adjustable speed drive on such an application may be only a few months. These drives easily can be integrated into commercial building control systems. In many parts of the country, electric utilities offer rebates for premium motor upgrades that usually offset the additional cost of premium motors over EPAct designs. Accelerated depreciation tax incentives are available from the government. Many of these programs also support the adoption of adjustable speed drives. Commercial building owners may benefit from federal tax deductions for certain energy-efficient upgrades. Help with energy conservation and best practices is available from the U.S. Dept. of Energy Industrial Technology Program at its “Save Energy Now” Web site. The EPA’s Energy Star program also is a source for assistance, enabling a company to partner and network with other companies on their successes. Motor Decisions Matter offers assistance in motor management. Motor and drive manufacturers, electric motor service centers, and power transmission distributors all can supply assistance. Companies can also contact local electricity suppliers and state energy offices for details on programs in their area. Consumption of electricity is a cost that can be controlled and managed. Malinowski has experience in industrial motor applications. He is an IEEE Senior Member and is a member of the IEEE Industry Application Society. He is Baldor’s representative to the NEMA Premium Efficiency Motor Program, the Motor Decisions Matter program, Energy Star Partners, and Standards for Energy Efficiency of Electric Motors in Europe. to the motor to make it more robust and eliminate downtime. More than 60% of all motor failures are a result of bearing failure. Selecting motors with better enclosures will protect bearings from contamination and prevent failure. Bearing selection for coupled or belted load will do the same. Many companies use NEMA Premium efficient severe-duty motors meeting IEEE 841-2001 standards that were developed for the petrochemical industry. These cast iron motors have many features to keep contaminants from entering the bearings, offer precision balancing and certified test data, and typically are supplied with a five-year warranty. The food processing industry is switching to all-stainless motors that are designed to be sanitized while keeping water from entering, and are built to NEMA Premium efficiency standards. A wide variety of motors designed for HVAC and pump applications also are available for retrofitting into commercial buildings. Electric motors Table 1 illustrates the operating costs for a typical HVAC or pump motor operating continuously with an electricity cost of $0.10 per kWh. It compares the operating costs of the average efficiency for a 20 hp motor from the 1998 DOE Industrial Assessment Survey to EPAct and NEMA Premium efficient motors. At the end of 20 years, the premium motor will save $13,960 in electricity at today’s electric rate. We expect the savings to be much higher as utilities continue to adjust their rates. Companies establishing green policies should consider electric motors as the keystone of their programs because the motors use so little of the company’s total electricity. Energy Star has a Green Buildings Program that allows buildings to be certified energy-efficient, which usually results in a higher building value. Only 11% of all companies have written motor specifications, only 12% of facilities have written motor rewind specifications, and 24% of facilities have not yet addressed energy. Yet more than 90% of motor decisions are made at the facility level. If motors are upgraded to NEMA Premium efficiency only on failure, it may take 18 to 20 years for complete replacement, according to the DOE. Companies should plan motor replacements before motors fail so the correct motor for the application is available. A plant survey should be conducted and each motor marked with instructions on what to do upon failure. Data collected from the survey should include motor voltage, horsepower, speed, efficiency, hours of operation, mounting type, and configuration of the motor. Companies can enter this data into software programs that analyze and calculate the potential savings when upgrading to NEMA Premium motors. These programs also show payback time and can handle offsets from motor repair or rebates. Another way to maximize energy savings is by using NEMA Premium motors with an adjustable speed control for pumps, fans, and other variable torque loads. Instead of adjusting fan flow with a damper, the motor speed is adjusted by an inverter control, which changes the voltage and frequency input to the motor, changing the motor speed. These variable torque loads follow the affinity rule that says when the speed is 58 Consulting-Specifying Engineer • DECEMBER 2008

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Consulting-Specifying Engineer - December 2008 Contents Viewpoint News M/E Roundtable ARC Awards New Construction Gold New Construction Silver New Construction Bronze Renovation Gold Renovation Silver A Green Approach to Air Conditioning Systems Turning Down the Lights Case Study New Products Equipment Lifecycles Advertiser Index Green Space Gas Technology Pure Power Supplement

Consulting-Specifying Engineer - December 2008

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