Practical motor efficiency assessment and improvement

By Rob Melaia, LHMarthinusen


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Published in:

Energy Efficiency Made Simple Vol III: Energy and enviroFiciency

November 2012 – Chapter 4: pages 51 - 55

Enquiries: email


With efficiency being such an important topic, it has become a more marketable entity and open to possible abuse. End-users are encouraged to have the efficiency of their plants, systems and components assessed and defined. Since motors are dominant users of available or utilised electrical energy, they are under the spotlight.

Of paramount importance in this respect is the fact that motors are inherently more efficient than their mechanical counterparts – a fact that readers are cautioned to consider. In other words, mechanical components are generally of much lower energy transfer efficiency than electric motors (and especially transformers) and therefore present far better opportunities for efficiency improvement.


The second most important priority is to ensure that any efficiency assessment (or measurement on which the assessments are based) is accurate. This is the primary intention of this article.


Take note

  • Motors do not ‘consume’ energy, they convert it, efficiently.
  • Motors are close rivals to transformers which only convert electrical energy.
  • Variable Speed Drives (VSDs) typically produce the best motor drive system efficiency improvements today.