Serving large horsepower motor loads that are located in rural areas has often been cost prohibitive for electric power suppliers and their customers. Due to the large current draw of electric motors during the first few seconds of startup, three-phase service is typically needed for motors of 10 horsepower size or larger. In many cases, the cost to provide three-phase service, at $18,000 to $28,000 per mile of line, could not be justified, and phase converters were not always reliable. But a new single-phase motor now being tested, may allow motors from 15 to 75 horsepower to be served from single-phase lines.

Known as the Written Pole^TM motor, this new technology is now being used on irrigation pumps and related applications. The manufacturer, Precise Power Corporation of Bradenton, Florida is selectively marketing the motor. Further research is being conducted by the Electric Power Research Institute (EPRI), the National Rural Electric Cooperative Association (NRECA), and the National Food and Energy Council (NFEC).

The Written-Pole^TM motor differs from conventional motors in many ways. Most induction motors use the attraction and repulsion of magnetic poles surrounding an internal rotor to cause the motor shaft to rotate. The Written-Pole^TM motor gets its name from a patented start-up technology which "writes" poles on a magnetic layer surrounded by an external rotor. Single-phase motors will draw 6 to 12 times their normal running current during start-up. The Written-Pole^TM motor draws only two times its running current at start-up.

The most logical "first use" application for this motor will be as a power source for remote irrigation pumps. This is by far the most attractive market because of the number of potential sites, the value to electrical utilities in serving this seasonal peaking load with single-phase service, and the potential to offer a pre-engineered pump/motor "package" which avoids costly on-site engineering.

A dozen prototype motors are now in place at test sites in seven U.S. states and Canada. Applications include golf course irrigation, oil pumps, row crop irrigation, and small municipal water systems. Anyone interested in learning more about this breakthrough technology should call NFEC at 937-383-0001.