Abstract
When the pulsating torque of an electric motor is measured by an apparatus using a transfertype torquemeter, the measured value is not the absolute value of the pulsating torque generated by the motor but the torque transferred to the load from the motor. Therefore, the measured values of the pulsating torque by the apparatus vary with the mechanical constants of the apparatus and the frequency of the pulsating torque, even if the amplitude of the pulsating torque is constant.
This paper deals with the conversion of the measured value obtained by the apparatus into the absolute value of the pulsating torque. When the mechanical part of the apparatus is represented by an analog electric circuit whose circuit constants are the function of the mechanical constants of the apparatus and the frequency of the pulsating torque, the ratio of the absolute value to the measured value equals the ratio of the source voltage to the condenser voltage. Therefore, the absolute value of the pulsating torque may be obtained by the product of the measured value and the above-mentioned ratio. But the ratio is so complicated that the method of simplifying the ratio is investigated.
These results are applied to the measurement of the pulsating torque of a condenser motor. This paper shows that the experimental values agree well with the theoretical values. Finally the resonance condition of the measuring apparatus is discussed.
