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High efficiency motors: what the new regulations really mean

26 October 2010

A new harmonised European standard EN 60034-30:2009 will take the place of the old voluntary Eff motor classes. The first phase is less than a year away so machine designers need to be conversant with the regulations now. The good news is that the changes need not cost much more, and for the end user and the environment the results are entirely positive.

The new motor efficiency regulations apply to three-phase asynchronous motors in the power range 0.75 - 375kW, in two-, four- and six-pole designs; basically, this covers the vast majority of motors and those used in the construction of machinery. There are certain exceptions, however. For example, eight-pole motors, motors that are an inseparable part of a machine and those requiring a supply voltage over 1,000V are exempt. Nonetheless, the scope of the legislation is predicted by the UK government to be sufficient to arrest the current increase in electric motor energy consumption. This is no mean feat bearing in mind the huge number of motors in service and the fact that they consume nearly 40% of the nation’s energy. Three new energy efficiency bands are defined in the new standard:

IE1 for motors of Standard Efficiency, equivalent to Eff2
IE2 for motors of High Efficiency, equivalent to Eff1
IE3 for motors of Premium Efficiency, no previous equivalent

Looking further ahead it is anticipated that an ever higher level of efficiency - IE4 - will be introduced. The actual limits of the three efficiency bands vary according to motor power. As an example in round figures, the minimum efficiency for a 7.5kW motor is 85% at IE1, 88% at IE2 and 92% at IE3.

Dateline
There is a phased introduction of the new regulations beginning in 2011. By June 16 2011 motors must meet the IE2 efficiency level as a minimum; by January 1 2015 motors from 7.5 to 375 kW must meet the higher IE3 efficiency level, or must be ‘equipped’ with a variable speed drive. By January 1 2017 the 2015 regulations are extended down to motors of 0.75kW.

The regulations cover motors that are “placed on the market”. This means motors delivered from motor manufacturers and their subsidiaries, including replacements for existing motors. Old stock at independent distributors or at machine manufacturers can still be sold, and the repairing and rewinding of old motors is permissible.

Thus any new machine or old machine requiring a replacement electric motor will require compliance with the new regulations. For the end user this is almost invariably a benefit. Over the lifetime of an electric motor, energy costs amount to about 97% of the total costs of ownership. Therefore a 2-3% gain in efficiency can achieve big savings in the long term. Based on 8,000 hours per year, stepping up an efficiency level can give payback times on the extra investment of about two years. As a simple guide, if a motor is used for 2,000 hours a year or more, the advice is to buy a premium efficiency motor or a high efficiency motor with an inverter drive now.

There are strict requirements for the labelling of the motor rating plate. From June 2011 the following information must be shown on both rating plate and in the motor documentation: lowest efficiency at 100%, 75% and 50% rated load, the efficiency level (IE2 or IE3) and the year of manufacture.

As has already been noted, from 2015 IE2 motors equipped with a frequency inverter can be used instead of IE3 premium efficiency motors. This is an attractive alternative and the IE2-plus-inverter combination will generally yield greater savings compared with IE, particularly if variable speed is required.

There is no expectation that the inverter must be integrated with the motor, although that is possible with certain product lines, and it is generally accepted that many customers will want to purchase motors their and inverters from different sources. Documentation requirements are not yet defined, but it would seem likely that a degree of self-certification will apply.

And what of the costs?
As the efficiency levels of motors increase, so does the cost, largely as a result of increased material and manufacturing costs. The increase in costs does depend on frame size; changing from IE1 to IE2 currently brings in a price premium of 20-30%. It is less on larger frame sizes, but as production volumes increase this is likely to fall to 10 to 20%. The premium to step up to IE3 is likely to be a little less. However, adding more copper to meet the higher efficiencies can also result in a change of motor dimensions – particularly an increase in motor length. In a minority of cases the motor frame size may actually increase (from IEC90 to IEC100, for example). Clearly, this is likely to cause problems when replacing motors on existing machine designs.

Many people would say the new regulations and efficiency bands are long overdue, as we finally begin to catch-up with countries like the USA and Australia. With the first phase less than a year away, we still have time to take the necessary steps for the changes, and the increases in motor costs are modest compared with their lifetime running costs. The big winners are going to be the end users, who will experience lower energy costs, and the environment, thanks to reduced CO2 emissions.

Lenze is well positioned to offer high efficiency products and packages. Right now as well as IE2 motors(illustrated) there is a comprehensive range of IE2 geared motors available up to 45kW. As a major manufacturer of frequency inverters, Lenze can offer packages of motor/geared motor and inverter that are IE3 equivalent. Furthermore there are other products such as the MF motor range that can deliver better than IE2 efficiency and 30% savings at part loads, plus regenerative braking units that can return excess energy to the mains supply.
 


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