VSDs, the environment and energy efficiency

By OEK Onwunta and MTE Khan, Cape Peninsula University of Technology, South Africa


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Published in:

Electricity+Control, March 2013 (pages 22 - 26)



Energy, especially tertiary energy, has remained the barometer of a nation's prosperity, but shortage of energy resources in the future has heightened the concern of the international community. This has resulted in the current emphasis on energy efficiency and conservation. Greater focus is on Electric Motor Driven System (EMDS) because of its high percent of energy consumption, most importantly in the industrial sector. Two approaches have been improvement on electric motors such as the use of efficient motors, and appropriate application of Variable Speed Drives (VSDs). Although the VSD is very efficient, it has some negative impacts on its electrical environment, for example, the effects of three-phase harmonics on circuits are similar to the effects of stress and high blood pressure on the human body. Also, its host or physical environment equally affects it. Therefore, this interplay deserves adequate consideration in the deployment of the VSD to achieve energy efficiency improvement of EMDS.


Take note:

  • Electric motor drives systems are the largest consumers of energy in industry.
  • VSDs offer an efficient means of managing the energy consumed by a motor.
  • VSDs do introduce harmonics and EMI into the environment and this must be considered when specifying and installing a VSD.