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Higher Efficiency Motors (HEMs)

Improvements in motor efficiency have been made possible thanks to new materials, better design and better manufacturing. An HEM may be regarded as a motor whose efficiency class is at least one level above the mandatory minimum. Motors have been labelled according to their performance. The new IEC standard (IEC60034-30,Rotating electrical machines - Part 30: Efficiency classes of single-speed, three-phase, cage-induction motors) defines three classes of motor efficiency, IE1, IE2 and IE3, where IE3 is the highest. Higher efficiency motors cost less to run than conventional motors. The savings they realise can quickly outweigh their additional cost to purchase and ensure long term financial benefits. An HEM typically costs more than the motor it is replacing, but its higher purchase cost is recouped by the power savings it makes during its operational life. The cost difference depends on the motor size and efficiency classification. For example when working near full load a typical 11kW IE3 motor (which is at least 91.4% efficient) will be around 1.6% more efficient than an IE2 equivalent and might cost up to £200 more to buy. If the IE3 motor was running continuously, you’d save around 1,290kWh a year compared to the IE2 equivalent. With electricity costing 8p/kWh (including Climate Challenge Levy), this gives a £100 saving each year, paying back your additional investment cost in 24 months. If you were upgrading from an IE1 or lower class motor the savings will be even more. In 2009 the European Commission announced mandatory minimum efficiency requirements for AC induction motors that are being placed on the market or put into service, according to the following stages: - Stage 1. From 16 June 2011 All motors must meet the IE2 efficiency level. - Stage 2. From 1 January 2015 Motors with a rated output of 7.5kW to 375kW must meet either the IE3 efficiency level, or the IE2 level and be equipped with a variable speed drive. - Stage 3. From 1 January 2017 Motors with a rated output of 0.75kW to 375kW must meet either the IE3 efficiency level, or the IE2 level and be equipped with a variable speed drive. What this means in practice is purchasers can be confident that most AC induction motors on the market will at least meet the specified efficiency levels from the dates specified. Purchasers should note that some motor types are exempt from the requirements, such as those designed for operation in potentially explosive atmospheres, and so are advised to seek clarification.
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