NEW ENERGYEFFICIENT MOTOR TECHNOLOGIES
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Increased energy efficiency requirements for drive systems have led to alternative motor technologies taking up the competition with traditional induction motors and AC drive applications.
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n the quest to improve the energy efficiency of drive systems, much effort has been spent on improving the efficiency of the electric motor. Through the introduction of a classification system for motor energy efficiency in the IEC 60034-30 standard, users are given a clear and easy framework for comparing motor efficiencies. With new higher efficiency classes being developed, users will have to get used to considering alternatives to the classic induction motor.
Classification of motor efficiencies Drive systems consume a major share of the electricity produced and used globally. In order to put more focus on the efficiency of electric motors and drive systems, the working groups of the IEC have created a framework for the measurement and classification of motor efficiencies with the standards IEC 60034-2-1 ‘Standard methods for determining losses and efficiency from tests’ and IEC 6003430-1 ‘Efficiency classes of line operated AC motors’. The standard IEC 60034-30-1 (2008) defines the motor-efficiency classes IE1, IE2 and IE3, as well as efficiency limits for each class and motor size.
28 WHAT'S NEW IN PROCESS TECHNOLOGY - MAY 2016
Additionally, in the latest version of IEC60034-30-1 Ed 1.0, a new class IE4 (super premium efficiency) is introduced. When classifying the efficiency of motors, it is important to take the size of the motor into account. An efficiency of, say, 90% is poor for a large motor but good for a small one — whereas a motor of class IE4 is always just about as good as it gets. Today there are only standards in place for line-fed motors, whereas requirements for defining the extra motor losses, and thus the change of efficiency, for motors connected to variable speed drives (VSDs) are not yet in place. Upcoming versions of the IEC 60034 family of standards are set to cover this aspect as well, but currently the efficiencies given by motor manufacturers are not suitable for direct comparison of motor efficiencies in VSD applications. The European Committee for Electrotechnical Standardization (CENELEC) has also created a framework for the comparison of the efficiency of drive systems in the standard EN 50598 - 2 ‘Ecodesign for power drive systems, motor starters, power electronics and their driven applications’. This standard also gives methods for defining the efficiency of a drive-plus-motor system (a power drive system or PDS) in a given application. By the end of 2016, the international version will be released as IEC 61800-9.
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