Induction motors are used in very large numbers in industry and account for about 65% of industrial electricity consumption. Over the last few decades, the efficiencies of the best motors have increased considerably. Following a voluntary agreement (1998) between European motor manufacturers (represented by CEMEP and the European Commission) the least efficient motors have been effectively eliminated from the market.
In the last few years, the technique of casting copper motor rotors has been perfected allowing further improvement in efficiency levels and offering a wide range of design options to manufacturers. While the efficiency of the motor is important, the design of the driven system is crucial; the motor must be well matched to the load and properly controlled, perhaps using a variable speed drive.
Typically, an electric motor can consume electricity to the equivalent of its capital cost within the first 500 hours of operation – a mere three weeks of continuous use, or three months of single shift working. Every year, the running cost of the motor will be from four to sixteen times its capital cost. Over its working life, an average of thirteen years, it may consume over 200 times its capital cost in energy.