Power and efficiency measurement of motor-variable frequency drive systems

This paper describes power and efficiency measurement in motor and variable frequency drive systems. The paper first presents an overview of existing international standards relating to motor and variable frequency drives systems and then discusses some of the challenges involved in measuring the power from the pulse-width modulated source. Differences in power measurements due to different power analyzer settings are demonstrated. Two induction motors were tested with sinusoidal supply and variable frequency drive supply to demonstrate power measurement challenges. The results of efficiency tests are compared for a five horsepower motor.