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Energy–Efficient Motors Energy–Efficient Motor Design – One Trend, Different Approaches

Author / Editor: Hans-Jürgen Bittermann / Dr. Jörg Kempf

Energy efficiency was at the top of the list of issues which were communicated to visitors at Achema 2012. In the aftermath of the show, the industry continues to look for ways of exploiting the opportunities that exist to save energy in chemical production. The quest has been particularly rewarding in drive engineering. Learn more about different approaches to energy-efficient motor design.

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A motor that literally takes the prize — KSB was the recipient of the German Industry Award and the PROCESS Innovation Award at Achema in recognition for its SuPreme motor generation (here shown with KSB’s Etanorm pump). PROCESS users then selected the design as the winner of the PROCESS User Award 2012.
A motor that literally takes the prize — KSB was the recipient of the German Industry Award and the PROCESS Innovation Award at Achema in recognition for its SuPreme motor generation (here shown with KSB’s Etanorm pump). PROCESS users then selected the design as the winner of the PROCESS User Award 2012.
(Picture: KSB)

Electric motors used to drive pumps, compressors, centrifuges, fans and linear axes account for roughly two-thirds of industrial energy consumption in Europe, making them a major cost factor. When you look at the cost breakdown, you find that the original procurement cost is actually the least expensive line item, contributing only 2.5% to total lifecycle cost. A gigantic 96% of the cost is incurred due to energy consumption. That is a classic case of “even free is too expensive”.

Energy Efficiency has Impact on Plant Design

This is now having an impact on the design of electric motors installed at chemical plants, which in many cases are (standard) asynchronous AC motors. Permanent-magnet synchronous motors are another option.

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Compared to asynchronous motors, they have significantly higher power density and are massively more efficient, particularly under partial-load conditions. The rotor contains high power density (permanent) magnets.

Synchronous reluctance motors, such as the KSB Supreme, are another alternative. No magnets are needed with this new design which has won three awards (see text box on page 36). The SEW Line Start Permanent Magnet Motor is a hybrid solution (asynchronous start up with subsequent synchronous operation — see box).

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