Consulting-Specifying Engineer - October 2007 - (Page 11)

On The Web VISIT W W W. C S E M A G . C O M Art of protecting electrical systems Site highlights • A question-and-answer with William Sako, executive vice president, RJA, Chicago, has been posted at www.csemag.com. Sako presented a CSE webcast “How to Address Integration and Interoperability for Campus Mass-Notification Systems.” “The art of weighing sustainable lighting solutions,” by Insiya Divan, lighting designer with Syska Hennessy’s Los Angeles office, explains that in order to deliver a truly sustainable lighting design, designers and engineers must weigh the art and science of illumination carefully. From the selection and implementation of lamp technologies to the integration of controls and energy-efficient components, all decisions affect the buildings’ overall sustainable characters. Go to the Green community at www.csemag.com. Energy-efficient data centers are here to stay, according to Bruce Myatt, PE, principal partner with EYP Mission Critical Facilities, San Francisco, and founder of the Critical Facilities Round Table. To read the full story, go to the Green community at www.csemag.com. • From 1965 through 1970, Consulting-Specifying Engineer’s predecessor, Actual Specifying Engineer, ran a series of articles on overcurrent protection. Due to the immense popularity of the 31 installments in the series, the authors, George Farrell and Frank Valvoda, PE, reprised the series in an updated version beginning in the Feb. 1989 issue of CSE. Over the years since the last installment ran in the late ’90s, we have received many requests to re-run this series. Consequently, we are making the series available as monthly installments at www.csemag .com. In September, we posted Part 12, “Approximating Short-Circuit Calculations for Conductors.” “Large or complex radial systems, closed-loop systems ,and networks require analysis by the per-unit method,” explained the authors. “However, for many straightforward radial systems, shortcut methods provide a quick, safe approach to determining fault currents for equipment application.” These estimates are valid even for final calculations, depending on the project’s size and the fault current available from the utility. This article describes a shortcut method for calculating the decrease in fault current caused by circuit conductors. The October installment in “The art of protecting electrical systems” series is about calculating short-circuit currents at secondary of transformers. While Part 12 presents a point-to-point method of calculating short-circuit currents, in Part 13 offers similar tables but ones that were updated to provide values of available fault currents at the secondaries of standard and low-impedance three-phase transformers. In November, look for Part 14 of this series in the Electrical community at www .csemag.com, which offers a step-by-step guide for calculating four types of singlephase faults. In the blogs at csemag.com David Sellers, PE, senior engineer with the Portland, Ore., office of Facility Dynamics and CSE’s “A Field Guide for Engineers” blogger continues his detailed analysis of energy use in engineered building systems. “In my previous post,” said Sellers, “I mentioned that using an electric resistance coil to generate a Btu of heat can be expensive relative to burning a fossil fuel on-site for the same purpose because of the difference between site and source energy.” If one only considers energy crossing the site boundary and the conversion efficiency of the electric heating coil, electric resistance heat seems like a the right choice. “So, why wouldn’t you want to use electric resistance heat and what makes it so expensive?” asked Sellers. “The answer to that question lies in the difference between site energy and source energy.” Sellers also has posted two parts of a series he titles, “Art, Craft, and Engineering” that discusses the “art and craft and struggle and passion” of developing HVAC control sequences. “When I first started to design, dealing with the realities that a design day imposed upon the system I was contemplating was all consuming,” said Sellers. “When it finally occurred to me that the design day represented only a tiny fraction of the operating reality my systems would have to deal with, I saw things from a new perspective; i.e. I had a new insight.” Read Sellers’ entire blog and comment at www.csemag.com. • Consulting-Specifying Engineer • OCTOBER, 2007 11 http://www.csemag.com http://www.csemag.com http://www.csemag.com http://www.csemag.com http://www.csemag.com http://www.csemag.com http://www.csemag.com http://www.csemag.com http://www.csemag.com http://www.csemag.com

Table of Contents Feed for the Digital Edition of Consulting-Specifying Engineer - October 2007

Consulting-Specifying Engineer - October 2007 Contents On the Web In the News M/E Roundtable How To Beat the Energy Codes Professional Practices Codes & Standards A Capital Job on Engineered Buiding Systems Going Green in Data Centers Overcurrent Protection: Fuses or Breakers? Third-Party Liability Management Report New Products Product Spotlight Jobs/Classifieds Specifier's Notebook

Consulting-Specifying Engineer - October 2007

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