Drives & Controls - High efficiency motors – the changes made simple

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

The new regulations apply to 3-phase asynchronous motors in a power range 0.75 to 375kW in 2,4 and 6 pole designs, basically the vast majority of motors and used in the construction of machinery. There are certain exceptions, for example 8 pole motors, motors that are an inseparable part of a machine and those with supply voltage over 1000V.

However, the scope is predicted by the UK Government Department of the Environment to be sufficient to arrest the current increase in energy and used by electric motors. This is no mean feat bearing in mind the massive number of motors in service and the fact they consume nearly 40% of the nation's energy.

Three new energy efficiency bands are defined:
IE1    for motors of Standard Efficiency, equivalent toEff2
IE2    for motors of High Efficiency, equivalent to Eff1
IE3    for motors of Premium Efficiency, no previous equivalent

Looking further ahead it is anticipated an ever higher level of efficiency IE4 will be introduced. The actual limits of these 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.

There is a phased introduction of the new regulations beginning in 2011:

16 June 2011 -  motors must meet the IE2 efficiency level as a minimum

1 January 2015 -  motors from 7.5 to 375 kW must meet the higher IE3  efficiency level, or must be ‘equipped' with an inverter variable speed drive

1 January 2017 -  the 2015 regulations are extended down to motors of 0.75kW

The regulations are based around the concept of 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. Repairing and rewinding 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 8000 hours per year, stepping up an efficiency level can give payback times on the extra investment of about 2 years. As a simple guide, if a motor is used for 2000 hours a year or more, an advice is to buy premium efficiency or high efficiency with inverter drive now.

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

As stated above, 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 + inverter combination will generally yield greater savings compared to IE3 if variable speed is required. There is no expectation the inverter will be integrated into the motor, although that is possible, and it is expected many customers will purchase motors and inverters from different sources. Documentation requirements are not yet defined, but it would seem likely a degree of self-certification will apply. 

As the efficiency levels of motors increase, so does the cost 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%, 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 higher efficiency levels can also result in changing dimensions. Often the motor length will increase. In a minority of cases the motor frame size may increase, for example from IEC90 to IEC100. In turn this may cause problems on existing machine designs with replacement motors.

Many people would say the new regulations and efficiency bands are long overdue.  We are playing catch-up with countries like the USA and Australia. With the first phase a year away, we have time to take the necessary steps for the changes. Increases in costs are modest compared with the lifetime costs for motors. The big winners are the end users with lower energy costs and the environment as a whole.

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