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In the European Union (EU), variable-speed drives (VSDs) were identified as the motor systems technology having the most significant electricity savings potential. In the EU, the identified economic electricity savings potential with the application of VSDs, by the year 2015, in industrial and tertiary sectors, are 39 and 8 TWh/year, respectively. However, only a small percentage of this potential is being used. In this paper the characterization of the current market of the VSDs is presented, including the average prices, the installation costs, and the total sales in each EU country, per power range. Selected VSD applications are presented. The key barriers to a wider application of VSDs are identified. In particular, the power quality and reliability problems associated with the use of VSDs are presented and possible technical solutions are discussed. Index Terms--Electric motor efficiency, electricity conservation, energy-efficient motor systems, market transformation, motor drives, motor systems, variable-speed drives (VSDs).

Since 1998, 817 motor efficiency test data sets, in the 1-500-hp (0.75-375 kW) range have been collected from several sources in different countries around the world, for 50 and 60 Hz. The test data include the motor efficiency using the IEC 34-2 and IEEE 112-B test standards, and the quantification of the stray load losses (SLLs), using the IEEE 112-B method. In 125 cases, the test data include the efficiency computed with both methods. The aim of this paper was the quantification of the discrepancy between the two mentioned standards, and to establish an approximate method to allow the comparison between motors tested with the two standards. Based on the significant number of collected motor data sets, it was concluded that, when compared to the IEEE 112-B standard, the IEC 34-2 standard is less accurate, and gives typically higher efficiency values, mainly because of the SLLs estimation procedure. The IEEE 112-B SLLs computed values are typically higher than the IEC SLLs predefined values, on average of 1.0 and 0.8 percentage points for 50-Hz and 60-Hz motors, respectively. Also, the average SLLs values vary slightly with the motor power. Using efficiency measurements made with both standards on the same motors, it was possible to confirm that the SLLs are the main reason for the observed discrepancy in the efficiency values. The results of the analysis carried out in this paper offer the possibility of comparing the efficiency of motors tested under the IEC 34-2 standard with motors tested with IEEE 112-B, leading to a choice of the most cost-effective option. This paper also provides a key contribution to the ongoing revision of the EEC 34-2 standard. Index Terms--Efficiency testing standards, induction motors, market transformation, motor testing, stray load losses.