Assessment of induction machine efficiency with comments on new standard IEC 60034-2-1

The paper assesses the efficiency of induction machines and measurement uncertainties arising from various input-output testing methods used in industry. Existing testing standards vary in methodology, procedure and required instrumentation accuracy, thus leading to significant differences in the experimentally determined efficiency for the same induction machine tested to the different standards as well as by different testing personnel. This paper focuses on the recently published IEC standard 60034-2-1, with comparisons of its previous version (IEC 34-2), and IEEE 112-B. Five induction machines with ratings between 7.5 and 150 kW are carefully tested using these methods and power loss results are validated by a separate calorimeter. Through theoretical analysis of measurement uncertainty using realistic perturbation-based estimation (RPBE) on these results, IEC 60034-2-1 is assessed in terms of its effectiveness and improvements over its previous version. Attention is paid particularly to these factors significantly impacting the machine efficiency such as determinations of stray load losses (SLL), stator winding resistance, stator winding temperature, and detailed specifications of testing procedures.