Motor Test Report 30 
Horsepower Single-Phase Written-Pole^®  Motor 
Page 5

Prototype Written-Pole^® Motor
The prototype motor tested at Hydry Quebec's LTEE facility in Shawinigan, Quebec was a 30 horsepower, 1800 rpm, 230 volt, single-phase, Written-Pole™ motor housed in an aluminum frame with critical dimensions matching the NEMA 326T frame specification and weighing approximately 650 lbs. While the prototype Written-Pole® motor is a permanent magnet synchronous machine, its basic construction is similar to that of a conventional induction machine. The motor utilizes a stator and rotor design comparable to those used in conventional capacitor start/run single-phase induction motors. Unlike previous Written-Pole™ designs, which utilized a high inertia external rotor design, the internal rotor prototype has a conventional internal rotor layout resulting in reduced start times and increased efficiency when compared to earlier designs. 

There are however several notable differences when compared to conventional electric motors. The rotor surface features a continuous layer of ferrite material and a high resistance rotor design that utilizes steel bars instead of the more commonly used aluminum or copper bars of conventional designs. The stator features a concentrated winding, which when even energized, creates a powerful magnetic field used to induce magnetic poles on the ferrite material while the motor is in operation. These features allow the motor's manufacturer, Precise Power Corporation of Bradenton, Florida, to design single-phase motors with much lower starting currents and higher operating efficiencies than conventional designs. The Written-Pole® prototype is designed for starting currents of less than 2.0 per unit or twice the motor's rated operating current. The AC permanent magnet design contributes to the prototype's high operating efficiency and low temperature. As a result of these advantages, precise Power Corporation is able to manufacture single-phase motors in rating of 60 horsepower, or greater, with frame sizes and weights approaching those comparable three-phase motors. 

Testing Laboratory 
All laboratory testing was conducted under the supervision of Hydro Quebec personnel at Hydro Quebec's LTEE test facility in Shawinigan, Quebec. LTEE's motor test laboratory is certifies by the Standards Council of Canada and recognized by the National Voluntary Laboratory Accreditation Program (NVLAP) administered by the National Institute of Standards and Technology. Hydro Quebec has been a leader in the field of motor efficiency verification testing during the past decade and has participated actively on various CSA, IEEE, and IEC technical committees pertaining to motor efficiency testing.