Electric Motor Efficiency under Variable Frequencies and Loads
Publication: Journal of Irrigation and Drainage Engineering
Volume 134, Issue 2
Abstract
This paper details a study performed by the Irrigation Training and Research Center to determine motor performances under varying speeds [induced by a variable frequency drives (VFD) controller] and loads. A further goal of the study was to provide sufficient information to designers so that they could estimate total pumping plant power usage with a VFD-controlled installation. Motors were tested with a VFD as well as across-the-line. On average, the relative efficiency of the electrical system with a VFD may be approximately 8% lower than the relative efficiency of a properly designed, full-load across-the-line system. If one considers actual field operating conditions this 8% is misleading because overall energy savings can be obtained with VFDs due to their ability to properly adjust speeds to meet actual field conditions.
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Acknowledgments
Funding for this project was provided by the California State University Agricultural Research Initiative Project No. 05-3-009. Funding was also provided by the California Energy Commission Public Interest Electric Research (PIER) Program, Agreement No. 400-99-014, and the U.S. Bureau of Reclamation Grant No. 04FG210013. Donations were received from Emerson Motor Company (75, 50, and 20 hp premium efficiency motors), Thoma Electric of San Luis Obispo (technical assistance for the electrical installation), Pacific Gas and Electric Co. (pressure gauges), and Branom Instrument Co. of Sacramento (Danfoss VFD controller).
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Information & Authors
Information
Published In
Journal of Irrigation and Drainage Engineering
Volume 134 • Issue 2 • April 2008
Pages: 129 - 136
Copyright
© 2008 ASCE.
History
Received: Dec 2, 2006
Accepted: May 15, 2007
Published online: Apr 1, 2008
Published in print: Apr 2008
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