Electricity + Control May 2019

DRIVES, MOTORS + SWITCHGEAR

Independent components Using automatic motor adaptation, motor- independent drives can deliver optimal perfor- mance of any motor just as well as the typical bundled motor and drive package. The motor-inde- pendent solution offers efficiency on par or some- times better than the bundle, due to its ability to cater for the diverse issues beyond IE class. Motor-independent drives developers have high stakes attached to running all motor tech- nologies and will adapt to every new tech- nology that arises. Due to the motor adapta- tion being software-based, it is possible to upgrade installed drives to compatibility with new motor technologies possibly not even in- vented at the time of the drive installation. Mo- tor independence is therefore inherently valu- able in retrofit where flexibility to choose the best motor for the task is an important consideration. As noted, motor-independent drives suppliers continually test new motor technologies in order to develop new algorithms for compatibility. Then they test to validate the optimised efficiency. So when choosing the right motor technology for the task, all the relevant data required for deci- sion making is readily available from the motor- independent drives supplier. Using motor-independent drives also opens other opportunities in that independently opti- mised components can be adapted to a variety of applications, whereas a bundled package is often optimised for a particular use case. The machine builder, with the required expertise, then has the opportunity to design the highest-performance drive/motor system for a specific niche application. Cost of labour Commercial considerations of course influence the choice in optimising performance by purchas- ing each component individually. Individual speci- fication and purchase of components is a labour- intensive process. It may therefore be more eco- nomical to choose a bundle, outsource respons- ibility and sacrifice some of the performance, or it may be more economical to choose motor and drive individually and achieve top-tuned perfor- mance.

In summary The advantages of a bundled motor-drive pack- age are that there is a single point of purchase, everything matches as it should, and lines of com- mercial responsibility are clean-cut and well-de- fined. However, in the long term it can become costly and limiting, especially in breakdown and retrofit situations. The alternative, a motor-independent drive combined with a selected motor, also has its ad- vantages. Financially, it offers the advantage of future-proofing – as the options remain open to use new generations of motor technologies over a long plant life. And to fine-tune performance to the optimum for a specific application, selecting in- dividual components is usually the best approach. The choice of motor-drive bundle or motor- independent drive combined with a selected mo- tor depends on the circumstances, on the required efficiency and performance, as well as on softer factors such as long-term relationships and trust. □

About the author Anna Hildebrand Jensen is an engineer from the University of Queensland, Australia, 1989. She has worked in the mining, construction and renewables industries in research and development, production and marketing roles. She has been with Danfoss as a technical writer since 2010.

Electricity + Control

MAY 2019

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