Appliance Design - January 2008 - (Page 31)

MOTORS S.S. WHITE Flexible Shafts ® ROTARY POWER & FLEXIBILITY Advantages of Flexible Rotary Shafts � Better This exploded view of an ebm-papst 1.5 HP EC fan motor with integrated electronics and fan blade. axial fans running at 4-pole speed and require about 16 W shaft power. The smallest walk-in coolers use 10-in. and 12-in. axial fans with 1,550-RPM motors that produce 1/15 HP. While ECM is the relatively new kid on the speed-control block, there are various other means to vary speed and control different motors. Speed reduction with small AC induction motors is often done with variable-voltage methods such as using inline capacitors, TRIACS (a bidirectional switch), or tapped motor windings, says Hauer. He cautions though, that motor efficiency is reduced significantly and the motor temperature rises. “This is why evaporator fans and small condenser fans are seldom speed controlled with voltage reduction,” he says. In terms of industrial and large, commercial walk-in coolers, many now use variablespeed motors with electronic drives. Large condenser fans are becoming equipped with continuously variable control instead of on/ off operation and often use just one TRIACcontrolled lead-fan. “The challenge here lies in making the electronics withstand the elements. TRIAC motor control is not suitable if acoustic noise is of concern,” says Hauer. For refrigeration products that employ 3-phase equipment, it may appear appealing to install variable-frequency drives (VFDs). Hauer cautions that careful evaluation is then necessary to prevent motor failures from VFD generated voltage spikes and common-mode currents arcing through the motor bearings. Because the VFD itself has some losses, electricity savings can be negated if the refrigeration load profile requires high fan speed. Performance than Universal Joints Installation Costs than Solid Shafts � Easily � Lower Maneuver Turns and Bends � Lightweight Powerful and � Isolate � High Vibrations Efficiencies � Economical S.S. White® is the World Leader in the design and manufacture of Flexible Shafts. We manufacture over 25 million Flexible Shafts each year for the Aerospace, Medical, Appliance, and Automotive industries. We take special pride in our responsiveness to customer needs and our innovative solutions to our customers’ most difficult design problems. 732.752.8300 www.sswhite.NET For more Information Enter 109 applianceDESIGN January 2008 31 www.applianceDESIGN.com http://www.sswhite.NET http://www.sswhite.NET http://www.appliancedesign.com

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Appliance Design - January 2008 Contents Editorial Shipments/Forecasts News Watch Makers of Commercial Refrigeration Equipment Turn to Variable-Speed Motors to Improve Energy Efficiency. New Motor Design and Control Scheme Makes Brushless Motors More Economically Feasible for a Wider Range of Applications. External Gas Molding, a Relatively New Technique, Solves Many of the Challenges Associated with the Injection Molding of Large Plastic Parts. Plastic Housings Offer Many Benefits: EMI Protection Isn't One of Them. But, New Materials and Techniques are Solving that Problem. Choosing the Optimal Strategy for Effective EMI Shielding Depends on Both Mechanical and Electrical Requirements Ethernet-Enabled Microcontroller Makes Networking Schemes Easier and More Cost Effective to Implement The Ever-Changing Array of Microcontroller Memory Options Makes it Imperative to Keep Abreast of What's Available to Determine the Optimal Choice for an Application. A Vast Range of Components and Finished Products will be Exhibited at the Country's Preeminent HVAC/R Show, AHR Expo, which is Scheduled for Jan. 22-24 in New York. Advertiser's Index Association Report: PRBA

Appliance Design - January 2008

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