Measurement of Electromagnetic Air Gap Torque Produced by a Syschronous Motor During Starting

At the present time there is no standard test procedure for the determination of the magnitude of the time varying (pulsating) component of electromagnetic air gap torque produced by a synchronous motor during the starting period. The theoretical basis and/or limitations of various test methods currently used to determine the magnitude of torque pulsations are summarized in this paper, with emphasis placed on methods utilizing measurements of electrical quantities (i.e., flux, current) to determine torque. The results of tests performed on a 100 horsepower, 1200 rpm synchronous motor indicate satisfactory correlation between the power input method, the search coil method, and an experimental method of torque measurement.