Consulting-Specifying Engineer - July 2008 - (Page 8)

Letters Letters Send your letters to Michael Ivanovich, editor-in-chief, Consulting-Specifying Engineer, 2000 Clearwater Drive, Oak Brook, IL 60523, or via e-mail to michael.ivanovich@ reedbusiness.com. Letters should be no longer than 200 words, and may be edited for space, style, spelling, and grammar. Mentoring HVAC engineers I want to congratulate Timothy M. Scruby, PE, for his excellent article, “Mentoring HVAC engineers,” in the May 2008 issue (page 30). I also have done a lot of mentoring. As a part-time associate professor at Polytechnic University of Puerto Rico, I have taught an air conditioning design course since 1990 and I am proud of the accomplishments of more than 400 ME students whom I have taught. This course has opened doors to my students in the fields of refrigeration and HVAC as contractors, consulting engineers, or employees of industry giants such as Trane, York, Carrier, McQuay, Daikin, and Mitsubishi Electric. The mentoring I gave them, which followed almost all the tips Scruby mentioned in his article, has provided these young engineers, including more than 20 who have worked in my firm, the necessary jumpstart to a successful career in the HVAC industry. LUIS GONZÁLEZ JR., MSME, PE MECHANICAL ENGINEERING CONSULTANTS SAN JUAN, PUERTO RICO Energy-efficiency measures The Philadelphia chapter of ASHRAE is doing several things to support energy conservation. First, it is the first chapter of a professional organization to sign up for the city’s Green Office Pledge program (see www.greenofficepledge.org). Second, the Philadelphia chapter is presenting an all-day seminar on Green Lighting on Sept. 23 at the Crowne Plaza Hotel, Philadelphia. And third, as a member of the chapter’s board of managers, I submitted a change to ASHRAE/IESNA Standard 90.1 to add the word “luminaire” or other source system. This is because many contractors still use the word “fixture,” and may not be aware of the newer source/systems like light pipes, glass fiber optics, or organic LEDs (OLEDs), all of which are more energyefficient than conventional bulbs and lamps. GERSIL KAY CONSERVATION LIGHTING INTERNATIONAL AND BUILDING CONSERVATION INTERNATIONAL PHILADELPHIA Nuisance VFD shut-down or breaker tripping is often misdiagnosed as “a quirky drive problem”. However, what is usually happening is caused by a voltage spike through the cable insulation. Since the cable is self-healing the drive will operate normally after re-start and thus the real problem is missed. Don’t be fooled by cable/voltage problems— It isn’t a “quirky” VFD Use 5% impedance, harmonic compensated reactors for the best single stage reduction of harmonic distortion. dV/dT Filters are designed to protect AC motors from the destructive effects of peak voltages facilitated by long cable runs–The MTE dV/dT filter is guaranteed to meet its maximum peak motor voltage specification (150% of bus voltage) with up to 1,000 feet of cable between the filter and the motor. Sine Wave Filters provide a sine-wave output voltage when driven from PWM inverters with switching frequencies from 2 kHz to 8 kHz. For drive applications, these filters eliminate the problem of motor insulation failures and reduce electromagnetic interference by eliminating the high dV/dT associated with inverter output waveforms. Call or visit our web site for more information and the name of your nearest distributor. The typical VFD cable between drive and motor is rated at 600 volts, but the high voltage spikes produced by the drive can well exceed 600 volts, notably near the motor termination. MTE’s Motor Protection Filters will eliminate the need for costly VFD cable. And, the MTE Sine Wave Filter solution is a more cost effective means to solve the cable problem while also providing motor protection–which the VFD cable cannot do! MTE motor protection filters include RL Reactors, dV/dT filters and Sine Wave filters providing you a cost effective and comprehensive line-up to solve virtually any motor protection problem. RL Reactors–Guard-AC reactors are compensated for harmonics (current and frequency), they are very effective at reducing the harmonics produced by a drive/inverter. .5 to 700 HP Motor, Drive and Cable Protection Find us fast at: Input #206 at csemag.com/quickResponse 8 Consulting-Specifying Engineer • JULY 2008 http://www.greenofficepledge.org http://www.mtecorp.com http://www.mtecorp.com http://csemag.com/quickResponse

Table of Contents Feed for the Digital Edition of Consulting-Specifying Engineer - July 2008

Consulting-Specifying Engineer - July 2008 Contents Viewpoint Letters News M/E Roundtable 40 Under 40 Using Demand-Based Reset Strategies VFDs and Motors: Making the Right Match Grounding and Bonding Practices for Hazardous Areas Codes & Standards Case Study New Products Equipment Lifecycles Advertiser Index Green Space

Consulting-Specifying Engineer - July 2008

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