World's largest

single-phase induction Motor

On June, 24, 1997, a revolutionary motor was demonstrated near Twin Falls, Idaho, to

interested farmers. An off the shelf three-phase Baldor Motor has been changed by a unique patented connection into the largest single-phase induction motor in the world at 40 horsepower. Single-phase motors have been available to date usually only below ten horsepower. Many areas only have single-phase power. The Smith Motor runs on a single-phase power supply with three-phase economy and efficiency. The motor is installed to Cornell pump which delivers 1350 gallons per minute from canal to overhead sprinklers..

It has multiple advantages to the user:

Performance. Full load performance is superior even to that of a three-phase motor on a three-phase line.

Economy. For farms having only a single-phase line it means that farmers do not need to install expensive three-phase lines or resort to expensive inverters or diesel pumps. They can make use of this technology to run conventional low-cost three-winding (3-phase) motors up to 100 horsepower for agricultural purposes.

Availability. Large single-phase motors have not previously been available.. Now they are.

Efficiency. This 40 hp motor has 94.4 percent efficiency, and similar efficiencies can be expected in other installations.

It has multiple advantages to the power company:

Minimizes losses. Full-load current has almost unity power factor, and thus minimizes the power company transformer and distribution losses. Soft-start starting current is less than full-load current and also has unity power factor.

This Motor design was invented and patented by Otto J. M. Smith of Smith and Sun. This installation southwest of Twin Falls on the Idaho Power Co. single phase distribution lines had the generous support of Baldor Electric Co., Cornell Pump Co. and Idaho Power Co. The Natural Resources Conservation Service of the Department of Agriculture made the hydraulic design. This demonstration was also sponsored by Current Control, Waite Electric, Butte Irrigation and Griff Land and Cattle Company. The pump delivers 1350 gallons per minute to irrigate 188 acres of the Griff land.

All components are readily available at low cost because they are standard items in inventory. The components are circuit breaker, contactors, capacitors, relays, transformers, and an ammeter. No special manufacturing is needed. A new installation can be operating soon after the decision to purchase the patent license from Dr. Smith and assemble the components according to the Smith design. For every component, there are several suppliers making equivalent competing products, so that either the shortest delivery time or the lowest cost can be chosen by the consumer.

This motor is quiet and vibration free at full-load. This motor installed on single phase is robust and satisfactory for variations in the line voltage. The single-phase starting current is much less than the three-phase starting current. The single-phase power factor is much higher than the three-phase power factor. This is a more economical method than the extension of a three-phase line to a farmer.

This motor has 94.4 percent efficiency at 42.8 horsepower to an irrigation pump delivering 1350 GPM. With this method any three-phase motor can be changed into a single phase motor. Agricultural needs can use these new single-phase motors between ten horsepower and 100 horsepower.

This new single-phase motor has a unique patented connection of a capacitor circuit to the motor windings to make the full-load performance on a single phase line superior to performance on the three-phase supply. Full-load current has almost unity power factor which is preferred for power company single-phase lines. The soft start starting current is less than full-load current and is also at unity power factor.

Hi-efficiency polyphase motors can also be used on all air conditioners and freezers for single phase, saving substantial amounts of energy for consumers, and reducing the severity of summer afternoon power system overloads to inefficient air conditioners.

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What are they?

Single-phase ten horse power motor

World's most efficient single-phase induction motors

Three dimensional model of motor

Otto Smith's Home Page

Smith & Sun®

612 Euclid Avenue

Berkeley, California 94708-1332
EMAIL:
otto.enabler@olympus.net

Webmaster: cshock@fmtc.com

Patented by:
Otto J.M. Smith
Smith and Sun®