Standards for efficiency of electric motors permanent magnet synchronous motor technology

Permanent magnet synchronous motor technology IEEE INDUSTRY APPLICATIONS MAGAZINE  JAN j FEB 2011  WWW.IEEE.ORG/IAS B Y A N ´I B A L T D E A L M E I D A , FERNANDO J.T.E FERREIRA, ˜ O A.C FONG & JOA 12 E LECTRIC MOTORS IN INdustrial applications consume between 30% and 40% of the generated electrical energy world- wide In the European Union (EU), electric motor systems are by far the most important type of load in industry, using about 70% of the consumed electricity In the tertiary sector (nonresidential buildings), although not so relevant, electric motor systems use about one-third of the electricity consumed Their wide use makes electric motors particularly attractive for the application of efficiency improvements Despite the wide variety of electric motors available in the market, three-phase, squirrel-cage induction motors (IMs) represent, by far, the vast majority of the market of electric motors [1], [2] Higher efficiency electric motors can lead to significant reductions in energy consumption and also reduce environmental impact To promote a competitive Digital Object Identifier 10.1109/MIAS.2010.939427 Date of publication: 12 November 2010 1077-2618/11/$26.00©2011 IEEE © FOTOSEARCH of PMSM technology in that respect, which, in general, are significant New Motor Efficiency Classification Standard IEC 60034-30 [3] is intended to globally harmonize motor energy efficiency classes in general purpose, line-fed (direct on-line connection) IMs used in stationary applications, defined according to IEC 60034-1 [7] The classification standard also applies to IMs rated for two or more voltages and frequencies IMs in the 0.75–375-kW power range make up the vast majority of installed motor population and are covered by this standard For the application of IEC 60034-30 standard, motor efficiency and losses shall be tested in accordance with IEC 60034-2-1 [8] using a low uncertainty method, such as the “summation of losses” test procedure with stray load losses (SLLs) determined from residual loss—a procedure similar to IEEE 112-B [11] The rated efficiency and the efficiency class shall be durably marked on the rating plate In a motor with dual-frequency rating, both 50- and 60-Hz efficiencies shall be marked for each rated voltage/frequency combination Motors with full-load efficiency equal to or exceeding an efficiency class boundary are classified in that efficiency class As stated previously, IE1, IE2, and IE3 classes are normative [3], [4], [10] Motors covered by this standard may be used in VSD applications (for further information, see Application Guide IEC 60034-17); however, in these cases, the marked efficiency of the motor shall not be assumed to apply because of the increased losses from the harmonic voltage content of the VSD power supply Motors specifically built for operation in explosive atmospheres (according to IEC Standards 60079-0 and 61241-1) are also covered by this classification standard Some design constraints of explosion-proof motors (such as increased air gap, reduced starting current, and enhanced sealing) have a negative impact on efficiency Geared motors and brake motors are included, although special shafts and flanges may be used in such motors [10] According to the IEC 60034-25 standard, motors specifically made for converter operation with increased insulation, motors completely integrated into a machine (pump, fan, compressor, etc.) that cannot be separated from the machine, and all other nongeneral purpose motors (such as smoke-extraction motors built for operation in high ambient temperature environments according to EN 12101-3) are clearly excluded Special motors required by applications with a large number of start/stop cycles are also not covered by this standard The full-load, continuous-duty efficiency of these special motors is typically below standard efficiency because of the need to reduce rotor inertia In some countries (e.g., Australia and New Zealand), eight-pole IMs are included in energy efficiency regulations However, their market share is already very low (in Europe about 1% or less) Because of the increasing acceptance of VSDs and the low cost associated with fourand six-pole standard IMs, it is expected that eight-pole IMs will further disappear from the general market in the future Thus, this standard excludes provisions for eightpole IMs [11] The 50-Hz values for IE3 class are newly designed and set about 15% reduced losses above the requirements for IE2 class The 60-Hz values were derived from the 50-Hz values taking into account the influence of supply IEEE INDUSTRY APPLICATIONS MAGAZINE  JAN j FEB 2011  WWW.IEEE.ORG/IAS motor market transformation, a new international standard, International Electrotechnical Committee (IEC) 60034-30 [3], was approved in November 2008 to globally harmonize motor energy efficiency classes in general purpose, single-speed, line-fed, three-phase, squirrel-cage IMs In this standard [3], three efficiency classes are proposed, standard efficiency (IE1) [the designation of the energy efficiency class consists of IE (short for International Energy Efficiency Class), directly followed by a numeral representing the classification], high efficiency (IE2), equivalent to EPAct, and premium efficiency (IE3), equivalent to National Electrical Manufacturers Association (NEMA) premium In addition, in the last proposal of the IEC 60034-31 technical specification standard, a super-premium efficiency (IE4) is also proposed, intended to be informative, since no sufficient market and technological information is available to allow its standardization and more experience with such products is required All the IE1, IE2, IE3, and IE4 efficiency levels are defined for the 0.75–375-kW power range, equivalent to the 1–500-hp range Regarding the IE4 class, some European manufacturers see no technical feasibility to reach the first IE4 proposed levels with IM technology with the same IEC frame sizes (defined in [5]) as IE1/IE2-class IMs However, very highefficiency motors with permanent magnet (PM) rotor technology are being introduced in the market, which allow not only reaching but overtaking the proposed IE4 levels The IE4 class under consideration can be applied both to line-fed motors and inverter plus motor units For lowpower levels (up to 7.5 kW), it is clear that moving away from IM technology and considering emergent technologies such as PM synchronous motors (PMSMs), either electronically controlled (EC) or with an auxiliary cage in the rotor to allow direct line-start mains operation [18], can allow achieving efficiency levels significantly higher than those defined by premium IE3 class In this article, feasible minimum limits for IE4 class are analyzed, taking into account the estimated efficiency limits and rated efficiency for emergent or commercially best available line-start PMSM technologies The presented results can be useful to set up future international standard super-premium or IE4-class levels/limits The practicability and technical limits associated with the IE4-class efficiency levels proposed in [4] are addressed, taking into account technical and economical limitations It is expected that advanced technologies will enable manufacturers to design motors for the IE4-class efficiency levels proposed in [4], with mechanical dimensions compatible with the existing IMs of lower efficiency classes (e.g., flanges, shaft heights, or frame sizes as defined in standards EN 50347 [5] and NEMA MG1 [6]) NEMA frames sizes are larger than the IEC frame sizes, allowing the use of more active materials In addition, 60-Hz operation enables higher power density and higher efficiency levels with the same frame sizes Moreover, in the case of EC PMSMs, the electronic controller, inverter, or variable-speed drive (VSD) efficiency and its impact on the motor efficiency are taken into account during efficiency focused analysis Since most general purpose IMs are oversized (in the EU, the IMs’ load factor is, on average, slightly lower than 60% [2]), the part-load efficiency or their load dependency should be analyzed to underline the potential advantages 13 98 98 96 96 94 92 NEMA Premium at 50 Hz NEMA Premium at 60 Hz EPAct at 50 Hz EPAct at 60 Hz 94 Motor Efficiency (%) Motor Efficiency (%) 90 88 86 Four Poles 84 82 50 Hz, IE1 50 Hz, IE2 50 Hz, IE3 50 Hz, IE4 60 Hz, IE1 60 Hz, IE2 60 Hz, IE3 60 Hz, IE4 80 78 76 74 72 70 0.1 92 90 88 86 Four Poles 84 82 80 0.1 10 100 Motor-Rated Power (kW) (a) 10 100 Motor-Rated Power (kW) (b) 14 frequency on motor efficiency [4], resulting for four-pole IMs, in the levels presented in Figure for four-pole IMs This approach will enable manufacturers to build motors for dual rating (50/60 Hz) The levels of the IE4 efficiency class are envisioned to be incorporated into a future edition of IEC 60034-31 technical specification standard The goal is to reduce the losses of IE4 by about 15% relative to IE3 Technologies other than IMs will be required to meet IE4 levels [3] 100 Windage and Friction Losses 90 80 Core Losses 70 Loss Fraction (%) IEEE INDUSTRY APPLICATIONS MAGAZINE  JAN j FEB 2011  WWW.IEEE.ORG/IAS IEC 60034-30 and 31 efficiency levels and NEMA and EPAct minimum efficiency requirements for 60- and 50-Hz, four-pole IMs [10] 60 50 Stray Load Losses Rotor I 2R Losses 40 30 20 Stator I 2R Losses 10 0.75 1.5 5.5 11 18.5 30 45 75 110 160 250 Motor-Rated Power (kW) Typical fraction of losses in 50-Hz, four-pole IMs [10] All efficiency curves are given in mathematical formula in smooth form to allow for various regional and national distinctions for frame dimensions and motor sizes The approved IEC 60034-30 efficiency classification standard will harmonize the current different requirements for IM efficiency levels around the world, hopefully ending the difficulties that the manufacturers encounter when producing motors for a global market Additionally, customers will benefit by having access to a more transparent and easier to understand information Efficiency Limits for Line-Start Industrial Motors The relative importance of the five different kinds of IM losses depends on motor size, as it can be seen in Figure In small/medium IMs, I2R losses are dominant Since I2R losses remain constant for 50 Hz and 60 Hz as long as the torque is kept constant, the output power is 20% higher for the 60-Hz IMs, and although windage, friction, and iron losses increase with frequency, they play a minor role in IMs Therefore, most IMs develop a better efficiency at 60 Hz compared with that at 50 Hz, becoming easier to reach a high motor efficiency when the motor is designed for and operated at 60 Hz instead of 50 Hz The difference in efficiency between 50 and 60 Hz varies with the number of poles and the size of the motor In general, when compared at the same torque, the 60-Hz efficiency of low-voltage, four-pole IMs in the 0.75–375-kW power range is between 2.5% points (small motors) to less than 0.5% points (large motors) greater when compared with the 50-Hz efficiency [4], [10] Only large two-pole IMs may experience a reduced efficiency at 60 Hz because of their high share of windage and friction losses Another important issue is the load dependency of losses and its impact on the IM efficiency When considering EC IMs or PMSMs, those In the case of PM rotors with auxiliary squirrel-cage, considering the steady-state, synchronous operation, the rotor electric and magnetic losses are mainly due to the effect of negative- and positive-sequence magnetomotive force spatial harmonics in the cage, inducing stray currents, which will produce losses, vibration, and parasitic torque components Nevertheless, for an optimized stator winding and rotor cage, those effects can be neglected On the basis of the typical fraction of losses for fourpole, 50-Hz IMs presented in Figure and the 50-Hz IE3class efficiency levels presented in Figure 1, it is possible to 96 Motor Efficiency (%) 94 92 90 88 86 84 Four Poles 82 0.1 10 Motor-Rated Power (kW) 100 IE3 Efficiency Levels for 50 Hz IE3 Efficiency Levels for 60 Hz Adapted Ultrapremium Efficiency Levels for 50 Hz Commercial Ultrapremium Efficiency Levels for 60 Hz Commercially available ultrapremium efficiency 60-Hz, four-pole IMs [3], [12] estimate the maximum achievable efficiency level (at 50 Hz) resulting from the reduction of each loss component The new improved motor-rated efficiency resulting from the losses reduction is given by (1) and (2), where gnew is the new rated efficiency (in percent), gorig is the original rated efficiency (in percent), Dptotal is the total losses (in percent), l is the loss component identification (e.g., rotor I2R losses and stator core losses), pcomp_l is the loss component l (in percentage of total losses), and Dpcomp_l is the variation of loss component l (in percent) 12 10 Losses Reduction (%) Line-Start PMSMs with Auxiliary Rotor Cage 98 IE3 Versus Ultrapremium Four-Pole, 60-Hz IMs 0.75 1.1 1.5 2.2 3.7 5.5 7.5 11 Motor-Rated Power (kW) 15 Loss variation between IE3-class efficiency levels and commercially available ultrapremium 60-Hz, four-pole IMs [10], [13] IEEE INDUSTRY APPLICATIONS MAGAZINE  JAN j FEB 2011  WWW.IEEE.ORG/IAS efficiency variations are not critical, since frequency can be set as a function of the needed speed, and the magnetizing flux can be properly regulated to maximize the efficiency Excluding the use of amorphous steel sheets in the stator and rotor cores, which means that copper is used in the stator windings and conventional ferromagnetic steel sheets are used in the stator and rotor cores, the efficiency improvement of the industrial motors can be achieved mainly by improving the design and changing the rotor materials The use of copper in the rotor cage was an important step toward premium efficiency levels, maintaining the typical wound stator and frame size However, if the frame size is respected, such material change is not enough to reach super-premium levels although it allows to reach efficiency levels slightly higher than IE3 class Ultrapremium efficiency IM models are already commercially available, as can be seen in Figure [12] The efficiency gain over NEMA premium or IE3-class efficiency levels is nearly one percentage point for the 1–10-hp power range, meaning that losses were lowered from 6.2 to 11.4% (Figure 4) by means of improved design and use of copper in the rotor cage As expected, the efficiency gain decreases with the rated power This clearly shows the efficiency improvement potential limits associated with IMs, if standard frame sizes are respected Nevertheless, new promising technologies are being investigated, such as the single-speed non-EC line-start PMSMs (with auxiliary cage) and the EC PMSMs [16]– [31] The last technology is currently commercially available [13]–[19], but the first one is not yet commercially available (at least in large scale) because of the inherent problems related with starting torque and synchronization effectiveness reported in a number of studies [20]–[31] Considering PMSM technology as the best candidate for line-start, single-speed, super-premium motors, it is important to estimate the maximum achievable efficiency This can be done by assuming that the stator core and windings are optimized in terms of design and materials, regarding cost-effectiveness issues and large-scale manufacturing technological restrictions (e.g., the type of stator winding used) On that basis, only the rotor can be improved or changed In the case of PM rotors, there are two main options: with or without auxiliary squirrel-cage to allow line-start capability [18] Within the PM rotors, there are several types with surface or interior PMs, with or without rotor saliency, and conventional or claw-pole geometry [18], [32] 15 h  iÀ1 gnew ¼ 104 Á gorig Á 104 þ Dptotal Á 102 À gorig ð1Þ Loss Component Fraction (% of Total Losses) 60 Rotor I 2R Losses Stator I 2R Losses Core Losses 50 Dptotal ¼ 10À2 Á R5l¼1 pcomp l Á Dpcomp l : 40 30 20 10 Four Poles, 50 Hz 0.1 10 Motor-Rated Power (kW) 100 Assumed motor loss component fraction (in % of total losses) TABLE MATERIALS COMPARISON BETWEEN PMSM AND IE2-CLASS IM [15] 16 Copper (%) Magnets (%) PMSM 40 42 100 IE2-Class IM 100 100 In the following analysis, 50-Hz IE3-class efficiency levels are considered the original efficiencies The loss components, in percentage of total losses, are assumed as in Figure Using (1) and (2), three cases were analyzed in terms of efficiency gains by means of losses reduction: n Case 1: elimination of rotor electric I R losses n Case 2: case and 58% reduction in stator I R losses n Case 3: case and 60% reduction in the stator core losses The percentage reduction of stator electric I2R and core losses is adapted from the expected/typical motor active material volume reduction from IE2-class IMs to PMSMs, according to Table [15], assuming that the current density in stator windings and the magnetic flux density in the stator core are maintained constant On that basis, it is considered that stator core and stator I2R loss reduction is directly proportional to the respective volume decrease The results for Cases 1, 2, and are presented in Figures 6, 7, and 8, respectively, denoted as above-IE3-class efficiency levels, which evidence the possible efficiency gains associated with line-start PMSMs with auxiliary cage Line-Start Electronically Controlled PMSMs In the case of PM rotors without auxiliary squirrel cage, the effects referred to in the “Efficiency Limits for Line-Start 100 98 100 96 IE3-Class Efficiency Levels Above-IE3-Class Efficiency Levels (Case 1) IE4-Class Efficiency Levels 96 Motor Efficiency (%) 98 Motor Efficiency (%) IEEE INDUSTRY APPLICATIONS MAGAZINE  JAN j FEB 2011  WWW.IEEE.ORG/IAS Core Steel (%) ð2Þ 94 92 94 92 90 88 90 86 88 84 Four Poles, 50 Hz 86 82 0.1 84 Four Poles, 50 Hz 82 0.1 10 Motor-Rated Power (kW) 10 Motor-Rated Power (kW) IE3-Class Efficiency Levels Above-IE3-Class Efficiency Levels (Case 2) IE4-Class Efficiency Levels 100 100 Full-load efficiency levels after rotor I R losses elimination in four-pole, 50-Hz, IE3-class IMs, denoted as above-IE3-class efficiency levels (Case 1) Full-load efficiency levels after rotor I R losses elimination and stator I2R losses reduction in 50-Hz, four-pole, IE3-class IMs, denoted as above-IE3-class efficiency levels (Case 2) Industrial Motors: Line-Start PMSMs with Auxiliary Rotor Cage” section not exist, and therefore, the rotor losses are extremely low However, the motors with such rotors have to be EC by inverters (or VSDs) to be able to properly start 100 98 and reach synchronization In this case, there are additional losses associated with the VSD itself and in the motor because of the PWM voltage-related harmonic losses When integrated in the system, although the energy savings potential associated with speed regulation, VSDs have a negative impact on the full-load efficiency motor system because of their internal losses and to the additional high-frequency losses in the motor In Figures and 10, the VSD efficiency typical levels and variation of efficiency with load are presented 100 94 95 92 90 VSD Efficiency (%) Motor Efficiency (%) 96 90 88 86 80 75 1.1 kW Integrated VSD for IM 1.1 kW External VSD for PMSM 11 kW External VSD for PMSM and IM 70 84 Four Poles, 50 Hz 82 0.1 85 10 Motor-Rated Power (kW) 65 100 60 IE3-Class Efficiency Levels Above-IE3-Class Efficiency Levels (Case 3) IE4-Class Efficiency Levels 20 40 60 80 VSD Load (%) 100 120 10 Full-load efficiency levels after rotor I R loss elimination and stator I2R and core loss reduction in 50-Hz, four-pole, IE3class IMs, denoted as above-IE3-class efficiency levels (Case 3) 100 98 96 Motor Efficiency (%) 100 98 VSD Efficiency (%) 96 94 IE3-Class Efficiency Levels Above-IE3-Class Efficiency Levels (Case 4) IE4-Class Efficiency Levels 94 92 90 88 86 92 84 90 88 86 0.1 Four Poles, 50 Hz 82 0.1 Typical Full-Load Efficiency for Standard VSDs Full-Load Efficiency for High-Efficiency Four VSDs Poles, 50 Hz 10 VSD-Rated Power (kW) 100 11 100 Typical full-load efficiency levels for VSDs 10 Motor-Rated Power (kW) Full-load efficiency levels for motor-VSD units, considering rotor I2R loss elimination and stator I2R and core losses reduction in four-pole, 50-Hz, IE3-class IMs, and the VSD efficiency, denoted as above-IE3-class efficiency levels (Case 4) IEEE INDUSTRY APPLICATIONS MAGAZINE  JAN j FEB 2011  WWW.IEEE.ORG/IAS Efficiency for high-efficiency 1.1- and 11-kW VSDs [29] 17 Considering the impact of the inverter output PWM voltages on the motor efficiency as well as the inverter efficiency, the overall efficiency is given by (3), where gvsd is the VSD efficiency (in percent), gorig is the original efficiency of the motor (in percent), gnew is the motor-VSD unit efficiency (in percent), and Dgorig is the motor efficiency decrease (in percentage points)   gnew ¼ 10À2 Á gvsd Á gorig À Dgorig : ð3Þ Using (3), Case is analyzed in terms of efficiency reduction due to the efficiency of the VSD, and the results are presented in Figure 11 In this case, the impact of the VSD output PWM waveforms in the motor efficiency is not considered Comparison of Standard and Commercial Efficiencies Some manufacturers sell integrated PMSMþVSD solutions, which achieve full-load efficiency values significantly higher than IE3 class In Figure 12, the full-load efficiency of commercial PMSMþVSD units from two different manufacturers, as well as the estimated maximum achievable full-load efficiency levels for PMSMþVSD units, is shown It can be seen that, for the low-power range, efficiency improvements are still possible Materials Usage IE2-class IMs incorporate more active materials than PMSMs, as can be seen in Table and Figure 13 According to two PMSM manufacturers, PMSMþVSD units and IE2-class IMþVSD units have an equivalent manufacturing cost However, IE3-class IMþVSD units incorporate more materials and have a higher cost Moreover, considering that copper is not used in the rotor, IE3-class premium IMs incorporate much more material than IE2-class IMs Therefore, in variable-speed applications, when compared with IE3-class IMþVSD units, PMSMþVSD units use less active materials Even considering the additional rotor magnet cost, PMSMþVSD have lower costs, and they achieve significant energy savings, thus being more environmentally friendly As a consequence, in low-power range variable-speed applications, it seems advantageous to shift the market directly to IE4-class levels using PM technology, jumping through the IE3-IM technology 98 Four Poles, 50 Hz 96 94 18 Motor Efficiency (%) 90 88 86 84 Conclusions Growing environmental concerns and high energy costs emphasize the importance of considering the life-cycle costs of nonstandard technologies PM motors prove to be significantly more efficient than IMs, particularly in the low-power range Moreover, they have higher power factor and cooler operating temperature Former disadvantages, such as the 82 80 78 76 0.1 10 100 Motor-Rated Power (kW) 1.1 kW/Four Poles IE3-Class Efficiency Levels IE4-Class Efficiency Levels Estimated Maximum Efficiency for EC-PMSM (Case 4) Brand A, Four-Pole, EC-PMSM Brand B, Four-Pole, EC-PMSM Brand C, Ultrapremium-Class IM, Adapted to 50 Hz Brand D, Four-Pole, NonECLINE-Start PMSM IE1 IM_al IE2 IM_cu PMSM + VSD IE1 IM + VSD Line-Start PM One-Phase IM_al kg (kW) 12 us ym er o et s Po l ag n M pe r op C in im um ro n um Al ee l/I St St ee l or e Comparison between IE3-class and IE4-class efficiency levels, commercial EC PMSMs full-load efficiency (considering the VSD efficiency), precommercial non-EC line-start PMSM prototypes full-load efficiency, and the estimated maximum efficiency levels for EC PMSMs (considering the VSD efficiency), corresponding to the above-IE3-class levels (Case 4) presented in Figure 11 [3], [4], [12]–[15] C IEEE INDUSTRY APPLICATIONS MAGAZINE  JAN j FEB 2011  WWW.IEEE.ORG/IAS 92 13 Materials usage (kg/kW) in different motor technologies (Source: European motor manufacturer.) [17] N Bianchi and T Jahns, “Design analysis higher costs, have now been rendered and control of interior PM synchronous obsolete Therefore, even applications THE RELATIVE machines,” in Proc IEEE Annu Meeting, IAS that were exclusively limited to asynTutorial Notes, Oct 2004, pp 2.1–2.22 chronous motors for cost reasons can [18] M Melfi, S Evon, and R McElveen, “InIMPORTANCE OF duction vs permanent magnet motors,” IEEE now profit from the advantages of PM Ind Applicat Mag., vol 15, no 6, pp 28–35, motors For single-speed applications, THE FIVE Nov./Dec 2009 with direct mains operation, the IM [19] J Mazurkiewicz (2009) AC vs DC brushDIFFERENT KINDS still has a cost advantage, although new less servo motor Baldor Electric [Online] Available: www.motioncontrolonline.org/files/ developments in line-start PMs may beOF IM LOSSES public/ come a cost-effective alternative DCvsACBrushless.pdf With variable-speed applications, [20] G Yang, J Ma, J Shen, and Y Wang, DEPENDS ON low-power IMs (with VSD) lose in terms “Optimal design and experimental verification of energy efficiency, and they have simiof a line-start permanent magnet synchronous MOTOR SIZE motor,” in Proc Int Conf Electrical Machines lar cost to PMs (with VSD), which are and Systems, China, 2008, pp 3232–3236 therefore an advantageous option [21] F Libert, J Soulard, and J Engstrom, “Design Since the energy-saving potential of a 4-pole line start permanent magnet synassociated with super-premium IE4-class motors is large, chronous motor,” Proc Int Conf Electrical Machines, Belgium, Aug 25–28, 2002 Paper 153 and the technology to achieve such efficiency levels is already available to be produced in large scale, it makes [22] K Kiurihara and M Rahman, “High-efficiency line-start interior permanent magnet synchronous motors,” IEEE Trans Ind Applicat., sense to promote such motors, by means of proper classificavol 40, pp 789–796, May/June 2004 tion and labeling schemes and, in the near future, introducing [23] T Miller, “Synchronization of line-start permanent-magnet ac upgrade minimum energy performance standard (MEPS), motors,” IEEE Trans Power App Syst., vol PAS-103, pp 1822–1509, July 1984 particularly in the small-medium power ranges References Anı´bal T de Almeida (adealmeida@isr.uc.pt), Fernando J.T.E Ferreira, and Joa˜o A.C Fong are with the University of Coimbra, Portugal Ferreira is also with the Engineering Institute of Coimbra, Polytechnic Institute of Coimbra, Portugal de Almeida and Ferreira are Senior Members of the IEEE This article first appeared as “Standards for Super-Premium Efficiency Class for Electric Motors” at the 2009 Industrial and Commercial Power Systems Technical Conference IEEE INDUSTRY APPLICATIONS MAGAZINE  JAN j FEB 2011  WWW.IEEE.ORG/IAS [1] A De Almeida, F Ferreira, J Fong, and P Fonseca, “EuP Lot 11 motors, ecodesign assessment of energy using products, final report for the European Commission, Brussels, Belgium,” ISR-Univ Coimbra, Feb 2008 [2] A de 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(EEMODS’09), Nantes, Sept 2009, Paper 53 19 ... Hz 82 0.1 10 Motor- Rated Power (kW) 10 Motor- Rated Power (kW) IE3-Class Efficiency Levels Above-IE3-Class Efficiency Levels (Case 2) IE4-Class Efficiency Levels 100 100 Full-load efficiency levels... Single-Speed, Three-Phase, Cage-Induction Motors (IE-Code), Ed 1, IEC 6003 4-3 0, Nov 2008 [4] Rotating Electrical Machines—Part 31: Guide for the Selection and Application of Energy-Efficient Motors. .. for High -Efficiency Four VSDs Poles, 50 Hz 10 VSD-Rated Power (kW) 100 11 100 Typical full-load efficiency levels for VSDs 10 Motor- Rated Power (kW) Full-load efficiency levels for motor- VSD units,