Serving large horsepower motor loads, located in rural areas has often been cost prohibitive for electric power suppliers and their customers. Due to the large amount of current drawn by motors during the first few seconds of startup, three-phase electric service is typically needed for motor sizes of 10 horsepower or larger.
In many cases, the cost to provide three-phase service ($18,000 to $28,000 per mile) could not be justified, and phase converters were not always the best option. The only other choice was to use a diesel or gas fueled engine to power the load, often costing over $5,000 per month for applications like irrigation pumps. But a revolutionary new motor design is now available that does not require three-phase service, and can serve loads from 15 horsepower all the way to 100 horsepower.
Known as the Written-Pole® motor, this proven technology is being used on irrigation pumps and other applications located miles beyond three-phase lines. The manufacturer, Precise Power Corporation of Bradenton, Florida is marketing the motor nationwide.
The Written-Pole® motor differs from conventional motors in many ways. Most induction motors use the attraction and repulsion of magnetic poles surrounding the rotor to cause shaft rotation. The Written-Pole® motor gets its name from a patented start-up technology, which "writes" poles on a magnetic layer on the rotor. This results in a very low start-up (inrush) current, so single-phase service can be used.
Written-Pole Motor and
While conventional single-phase motors will draw six (6) to twelve (12) times their normal running current during start-up, Written-Pole® motors draw only two (2) times their running current while still delivering excellent starting torque. Therefore, it does not cause blinks or voltage sags for other customers on the line.
The most common "first use" application for this motor has been for remote irrigation pumps. Over 150,000 irrigation sites now use diesel or gas engines in the U.S. alone. This is by far the most attractive market for this motor for three main reasons:
1. The large cost savings to customers, as compared to using engines (fuel, oil and maintenance);
2. The value to electrical utilities in serving seasonal loads, using less expensive single-phase service;
3. The ability to offer a pre-engineered pump/motor "package" to overcome costly on-site engineering.
Hundreds of motors are now operating at sites in the U.S. and Canada. In addition to farm irrigation, applications include:
Golf course irrigation Small municipal water systems
Oil pumps Grain handling
Consumers who are interested in learning more about this breakthrough technology should visit the following web site: www.Written-Pole.com.
Electric power suppliers can call us here at the Rural Electricity Resource Council, 937-383-0001 and ask for Richard Hiatt.