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Motor efficiency: be ready for the new classifications

01 June 2009

Next year, motor manufacturers and users must begin to assimilate new efficiency classifications, as IEC 60034-30 implementation is rolled out in stages, between 2011 and 2017. This ‘harmonised’ standard removes the existing Eff ‘x’ classifications, which have been with us for the past ten years or more, and will avoid the need to test equipment against the plethora of existing international standards. Les Hunt reports

Motor variable speed drives undoubtedly make a big difference when it comes to implementing energy efficiency and carbon emissions reduction measures; sometimes the results are astounding, as we have reported many times in the pages of this magazine. However, perhaps less appreciated is the contribution that high efficiency motors can make, particularly when they are also under the control of a variable speed drive. It should also be noted that, thanks to their cooler running, high efficiency motors last longer and need less maintenance, as bearing re-greasing intervals can be extended – all contributing to lower life cycle costs.
According to a new survey from the market researcher, IMS, some three quarters of all ac induction motors sold throughout the world each year do not meet the minimum efficiency standards currently being set by governments. The US government, for example, requires motors between one and 200hp to meet the NEMA Premium efficiency level from December 2010. Clearly there’s a lot of ground to cover in a relatively short period of time, but IMS analyst, Steve Odom believes that the market for high efficiency motors will triple in revenue terms by 2011.

New standard beckons
We should, by now, have become used to the motor efficiency classifications Eff1, Eff2 and Eff3, which were introduced more than ten years ago. Of course, they remain valid today, but with the new IEC 60034-2-1: 2007 efficiency measurement standard fully ratified, the wheels are now in motion for the staged introduction of the new harmonised motor efficiency standard IEC 60034-30:Oct.2008.
This defines three new International Efficiency (IE) efficiency classes: IE1 (which, contrary to Eff1, is the lowest efficiency), IE2 and IE3 (defining ‘Premium’ efficiency, IE2 being equivalent to Eff1). The timetable for implementing this new standard requires that all motors must reach IE2 from June 2011 (2-, 4- and 6-pole; 0.75-375kW; up to 1,000V). Phase two, to be implemented from January 2015, requires that all motors in the range 7.5-375kW must meet the Premium efficiency category IE3 (single speed) or IE 2 (when controlled by a variable speed drive). From January 2017, motors with a rated output between 0.75 and 375kW must meet IE3 (single speed) or IE2 (when controlled by a variable speed drive)
In terms of measurement, the newly ratified IEC 60034-2-1: 2007, requires that the actual measured winding and rotor temperature losses are used based on an assumed ambient temperature of 25oC (more realistic for industrial environments, compared with the previous 20oC), and that the winding and rotor losses are calculated with actual temperature rise. Currently, these losses are calculated with a fixed 95oC temperature rise.
ABB’s Steve Ruddell – a stalwart energy efficiency campaigner – welcomes the new legislation but has some reservations about the extent of its impact. In particular, he would like to have seen the inclusion of ATEX motors within the new legislation. While accounting for 10% of the installed based, they are responsible for more than 10% of energy consumption. Mr Ruddell also questions why the legislation stops at 375kW when, in a typical process, plant motors rated above 355kW consume more than 29% of the total motor energy bill.
Another issue raised by Mr Ruddell involves the rewinding of motors. He believes that the legislation should address motor rewinds as well as new motors, and repairers should rewind to the latest applicable minimum efficiency standards, which, after 2011, will be IE2 and after 2015, IE3. But if this cannot be achieved because of stator slot design and so on, then the motor should be scrapped and a new one supplied. This will accelerate the swap out of the installed based.
Finally, what happens if manufacturers outside of Europe decide to ship motors that do not conform to the EU legislation? In Europe it is not clear how the legislation will be enforced. Who will carry out the enforcement? How will it be carried out? What will be the penalty for those failing to comply? These are issues that must be addressed before the deadlines are upon us!

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