Public Power - September/October 2007 - (Page 49)

The loss cost analysis results are very sensitive to the cost of money, so good information is needed. The interest rate to be used for the net present value calculations is best obtained from the community’s finance director or public service director. Information regarding present power costs may not be presented in usable form on the power invoice. If not, the wholesale provider or generation plant staff should be able to provide the data in the format needed. Information concerning future power cost should be available from the wholesale provider or from the generating plant staff if your community operates generation. Transformer loading practice is usually determined by the distribution system operators if the utility is not large enough to have an engineering department. Analysis of secondary factors, such as early retirement, is not included in the method since it can only effectively be done statistically for a large sample of units and, in my opinion, the attempt to analyze such secondary factors adds little value. Many system operators will limit the demand on a particular pole-mounted unit, not by changing it out, but rather by transferring some load from the unit to a new transformer installed in the load area. Commercial/industrial transformers are changed out if load growth for a particular customer exceeds expectations. The transformer may then spend a period of time in storage before it is installed in a new location. The net present value of the difference in cash flow at such a point in the future for a particular unit is usually small. For a large population of units, refinements to this analysis may be applicable, but only if good records are available to allow reliable prediction of the probable future life-cycle of the units evaluated. Although the information presented in the Distribution System Performance Improvement Guide is all that is really needed to undertake loss cost evaluations, those who want to dig a little deeper should read RUS Bulletin 1724E-301, available from the RUS Web site. Also, The Equivalent Hours Loss Factor Revisited, IEEE Transactions on Power Systems, Vol. 3, No. 4, November 1988, presents an excellent overview of the empirical equivalent loss factor equation and a discussion of the constants used in the equation. Considering the ease of performing loss evaluations based on the method presented in the Distribution System Performance Improvement Guide, there is no good reason not to be doing transformer loss evaluation for every transformer purchase. s Mark Feller is communications and substation superintendent for the city of Wadsworth, Ohio. Energize With an ASI Partnership Associated Systems Incorporated (ASI) establishes partnerships to implement and maintain the highest-quality, innovative IT solutions to utility companies. From accounting and finance to billing and customer service, ASI can partner with you to meet your changing needs and provide individualized results to enhance your efficiency, productivity and customer service. For more information, visit www.assocsys.com or call 888-232-1239. • Meets FAA Specifications! Color – Size – Shape! – International Orange • Tested and approved by major power companies! • Thousands still in service after 30 years • Universal attaching! Fits any wire .1" to 1"! • Installs in 5 minutes! • Withstands hail! • No maintenance! Does not slip, oscillate, chafe, cause electrolysis or harmonic vibration. • Ships in halves nested. 9, 12, 20, 24, 30, 36 and 52" balls & special sizes ava Call now 573-796-381 ext. 2001 Fax 573-796-3770 www.tanawiremarker.com TANA WIRE MARKERS P.O. Box 370, California, MO 65018 www.APPAnet.org SEPTEMBER-OCTOBER 2007 49 http://www.APPAnet.org

Table of Contents Feed for the Digital Edition of Public Power - September/October 2007

Contents Washington Focus 10 Questions Public Power (Every) Week Training Tomorrow’s Work Force What’s in Your Wallet? U.S. Lags in Broadband Deployment Now What? For Engineers Safety Community Broadband For Governing Boards Human Resources Hometown Connections Customer Service DEED Index to Advertisers Advertisers by Category Parting Shot

Public Power - September/October 2007

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.