Motor Test Report 30 
Horsepower Single-Phase Written-Pole^®  Motor 
Page 2

Additional testing demonstrated that modifications to the switching schemes for the start/run capacitors could further enhance the performance of the machine during part load conditions. Efficiency at part loads was improved from 77.7% at 24% loading to 83.8%, representing a 451 watt or 28% reduction in total losses. Similar results were achieved at 50% loading with a 214 watt or 15% reduction in losses. 

Locked rotor tests and starting tests were used to verify the prototype's starting performance. The locked rotor current was measured at 144 amps when rated voltage was applied to the motor terminal with the shaft locked. Locked rotor torque was measure at approximately 85 N-m or72% of rated torque. 

While the locked rotor torque is significantly lower than comparable three-phase designs, the dramatic reduction in locked rotor current when compared to conventional three-phase design yields significant reductions in temperature rise during starting cycles.