Real time monitoring of measurement uncertainty for Power Drive Systems with respect to EN 50598-2

This paper investigates the impact of the measurement uncertainty on efficiency of motors, drives, and power drive systems. According to European standard EN 50598-2, efficiency class definitions of motor and power drive systems should include the uncertainty of measuring instrumentation. This renders the choice of the uncertainty estimation model crucial, in order to guarantee a reliable class declaration. The proposed methodology follows the guidelines presented in EN 50598-2 for input-output technique, and accounts for the contribution of measurement uncertainty related to the accuracy specifications of the instruments and sensors. A LabVIEW based tool for automated sequencing and efficiency measurement is developed. The tool accounts for configuration of instruments, basic control of the drives for testing at different operating conditions, data acquisition, efficiency class declaration and online uncertainty calculation based on the method proposed in this paper. A series of tests are carried out on an actual motor drive system test bench for the experimental validation of the analysis. The tests allowed for precise evaluation of the feasibility of the test procedures described in the standard, especially in the case of motor drive testing. The analysis highlights the necessity of a well-defined uncertainty calculation methodology to ensure a reliable declaration of the efficiency class of the product (PDS) under test.