Electric drives and motors: Meanings, definitions, interpretations

The operations of most industrial loads require wide ranges of speed. These loads could be driven by hydraulic, pneumatic or electric motors. Three major means of achieving variable speed control in the industries are mainly mechanical, hydraulic, and electrical/electronic. Each of these control options has its strengths and weaknesses.

Electric motors, especially squirrel cage induction motors, have remained excellent prime movers even in mechanical and hydraulic speed controls. In both mechanical and hydraulic speed controls the electric motor is operated in constant speed mode and the actual variable speed achieved through belts, chains, pulleys, hydraulic pumps, valves and hydraulic motors.

However in electrical/electronic speed control variable speed is realised directly on the electric motor.


Take note

  • Exergy’ is the portion of total system energy that is actually available for conversion to useful work.
  • South Africa continues to use a relatively high amount of energy for every Rand of value added.
  • Power electronics plays a crucial role in industry and it can affect system efficiency.


Published as:

Electric drives and energy efficiency: Myriad meanings

By Onwunta EK Onwunta and MTE Kahn, Cape Peninsula University of Technology, South Africa

Electricity+Control, November 2012 (pages 4 -10)